Report  of  the 

Chicago 

Commission  on  Ventilation 
•1914 


The  Chicago  Commission  on  Ventilation  was 
organized  in  February,  1910. 


Copyright,  1915 

by 
Chicago  Commission 

on 
-Ventilation 


v  / 


Organization  Members 

Organizations  having  representation  in  the  Chicago 
Commission  on  Ventilation,  together  with  a  list  of  mem- 
bers: 

Chicago  Department  of  Health 
George  B.  Young,  M.  D.  E.  V.  Hill,  M.  D. 

Chicago  Board  of  Education 

John  Wilkes  Shepherd 

Illinois  Chapter  of  the  American  Society  of  Heating 
and  Ventilating  Engineers 

Samuel  R.  Lewis  James  H\  Da\:yP^ 

H.  M.  Hart 

-  • 

Illinois  Chapter  of  the  American  Institute  of  Architects 
George  Beaumont 

Illinois  Society  of  Architects 
Meyer  J.  Sturm 

Western  Society  of  Engineers 
Fred  J.  Postel 


Dedicated  to  one  of 
Humanity's  Greatest 
Assets — Public  H^Ith. 


Preface 

The  Chicago  Commission  on  Ventilation  is  now  in  its 
fifth  year,  and  this  is  its  first  publication.  This  publication 
appears  for  two  reasons : 

(1)  In  order  that  all  members  of  the  organizations 
holding  membership  in  the  Commission  may  have  a  de- 
tailed report  of  the  Commission's  work. 

(2)  In  order  to  meet  the  requests  from  cities  and  from 
civic  and  other  organizations  that  are  asking  for  reports  of 
the  work  of  the  Commission. 

This  report  comprehends : 

(1)  A  history  of  the  organization  of  the  Commission, 
including  a  statement  of  its  methods  and  working  principle. 

(2)  A  statement  of  some  of  the  problems  undertaken 
by  the  Commission. 

(3)  Reports  of  tests  made  by  the  Commission  on  the 
ventilation  of  passenger  cars,  picture  theaters,  an  experi- 
mental schoolroom,  an  office,  and  an  experimental  cabinet. 

(4)  The  opinion  of  the  Commission  on  phases  of  ven- 
tilation as  set  forth  in  resolutions. 

(5)  An  appendix  containing  a  description  (in  most 
cases   an  illustrated   description)    of  the   apparatus   and 
methods  used  in  the  tests  made  by  the  Commission. 

The  organizations  holding  membership  in  the  Commis- 
sion are  sufficiently  established  and  also  sufficiently  varied 
in  their  purpose  to  bespeak  the  value  of  its  findings.  It  is 
but  fair  also  to  state  that  almost  all  of  the  resolutions  em- 
bodied in  this  report  have  been  the  subject  of  careful  ex- 
perimentation, from  time  to  time,  by  members  of  the  Com- 
mission. 


Organization  of  the  Chicago  Commission 
on  Ventilation 

The  Chicago  Commission  on  Ventilation  was  organized 
in  February,  1910.  The  call  for  the  meeting  at  which  the 
organization  was  effected  was  made  by  Dr.  W.  A.  Evans, 
who,  at  the  time,  was  Commissioner  of  Health  of  the  City  of 
Chicago.  In  addition  to  Dr.  Evans,  the  following  named 
persons  were  present  by  invitation :  Messrs.  George  Mehr- 
ing,  W.  L.  Bronaugh,  and  Samuel  E.  Lewis,  members  of  the 
Illinois  Chapter  of  the  American  Society  of  Heating  and 
Ventilating  Engineers;  Dr.  F.  0.  Tonney,  Director  of  the 
Municipal  Laboratories,  City  of  Chicago,  and  Mr.  J.  W. 
Shepherd,  from  the  Public  Schools  of  the  city.  At  this 
organization  meeting,  Mr.  George  Mehring  was  elected 
chairman,  and  Mr.  J.  W.  Shepherd  secretary. 

A  COMMISSION  ON  VENTILATION  NEEDED. 

Full  and  free  discussion  on  the  general  subject  of  ven- 
tilation was  indulged  in  by  all  present  at  the  organization 
meeting,  and  some  of  the  conclusions  reached  may  throw 
light  on  the  purposes  and  methods  of  the  Commission.  All 
were  agreed  that  : 

(1)  In  the  construction  of  new  buildings,  ventilation 
is  not  receiving  the  consideration  which  its  importance  war- 
rants. 

(2)  Our  present  methods  of  ventilation  are  based  on 
standards  which  are  more  or  less  traditional  and  without 
scientific  foundation. 

(3)  All  the  factors  which  influence  the  ventilation  of  a 
building  are  not  understood. 

(4)  The  importance  of  ventilation  makes  it  most  de- 
sirable, if  not  entirely  necessary,  to  conduct  such  experi- 


8       .-.;;;.'.        .ORGANIZATION  OF  COMMISSION 

ments  as  will  make  the  practice  of  ventilation  a  branch  of 
applied  science. 

FIRST  REPRESENTATION  ON  THE  COMMISSION. 

At  the  time  of  the  organization,  the  Commission  con- 
sisted of  delegated  representation  from  the  Department  of 
Health  and  from  the  Public  Schools;  also  representative 
members  of  the  Illinois  Chapter  of  the  American  Society  of 
Heating  and  Ventilating  Engineers.  Soon  after  the  organ- 
ization was  effected,  the  three  members  who  belonged  to 
the  Illinois  Chapter  of  the  American  Society  of  Heating 
and  Ventilating  Engineers  were  authoritatively  delegated 
as  representatives  from  their  society. 

FORMULATION  OF  OPINION. 

From  the  beginning,  it  has  been  the  custom  of  the  Com- 
mission to  indicate  progress  or  clarify  opinion  through"  the 
medium  of  resolutions.  These  resolutions  are  formulated 
by  the  various  members  and  reported  to  the  Commission  at 
one  of  its  regular  meetings.  Eesolutions  must  be  reported 
at  least  one  meeting  prior  to  the  time  of  their  consideration 
and  adoption  or  rejection.  Moreover,  when  a  resolution  has 
been  adopted,  it  may  be  reconsidered  at  any  subsequent 
meeting. 

The  first  resolutions  were  necessarily  general  in  char- 
acter, but  aimed  at  fundamental  principles,  which  must  be 
considered  in  the  practice  of  all  ventilation. 

MEETINGS. 

It  has  been  the  custom  of  the  Commission  from  the  be- 
ginning to  hold  meetings  on  the  first  and  third  Tuesdays  of 
each  month,  throughout  the  year,  with  the  exception  of  the 
summer  months.  Call  meetings,  however,  sometimes  are 
issued  even  during  the  vacation  period. 

ADDED  MEMBERSHIP. 

Early  in  the  year  1911,  it  became  evident  that  in  order 
to  be  most  effective  the  Commission  should  have  member- 


ORGANIZATION  OF  COMMISSION  9 

ship  from  the  Architects'  organizations  of  the  city.  Ac- 
cordingly, an  invitation  was  extended  to  the  Chicago  Archi- 
tects '  Business  Association  and  to  the  Illinois  Chapter  of 
the  American  Institute  of  Architects  to  appoint  one  delegate 
each  to  be  a  member  of  the  Commission  on  Ventilation. 
Accordingly,  Mr.  W.  H.  Tomlinson  was  delegated  from  the 
Illinois  Chapter  of  the  American  Institute  of  Architects, 
and  Mr.  Meyer  J.  Sturm  from  the  Chicago  Architects* 
Business  Association. 

At  the  close  of  the  year  1912,  Mr.  W.  L.  Bronaugh  and 
Mr.  George  Mehring  found  it  necessary  to  withdraw  from 
the  Commission.  Accordingly,  Mr.  H.  M.  Hart  and  Mr. 
James  H.  Davis  then  became  members  of  the  Commission 
from  the  Illinois  Chapter  of  the  American  Society  of  Heat- 
ing and  Ventilating  Engineers.  At  the  same  time,  the  pres- 
sure of  outside  work  also  compelled  Mr.  W.  H.  Tomlinson 
to  withdraw  and  Mr.  George  Beaumont  became  the  repre- 
sentative from  the  Illinois  Chapter  of  the  American  Insti- 
tute of  Architects. 

When  Dr.  George  B.  Young  became  Commissioner  of 
Health  in  February,  1912,  he  accepted  membership  in  the 
Commission.  In  January,  1912,  the  City  of  Chicago  estab- 
lished a  ventilation  division  of  the  Bureau  of  Sanitation, 
with  Dr.  E.  V.  Hill  in  charge.  It  was  the  sense  of  the  Com- 
mission that  the  city's  Chief  Ventilating  Inspector  should 
be  a  member  of  the  Commission  on  Ventilation,  and  Dr.  Hill 
became  a  member  in  July,  1912. 

The  Western  Society  of  Engineers  accepted  represen- 
tation in  the  Commission  and  accordingly  Mr.  Fred  J.  Pos- 
tel  became  a  member  of  the  Commission  in  January,  1914. 

THE  ENLAKGED  MEMBERSHIP  OF  THE  COMMISSION. 

The  Chicago  Commission  on  Ventilation,  as  now  con- 
stituted, is  a  delegated  voluntary  organization,  composed  of 
representation  from  the  following  organizations : 

Department  of  Health  of  the  City  of  Chicago. 

The  Illinois  Chapter  of  the  American  Society  of  Heat- 
ing and  Ventilating  Engineers. 

The  Public  Schools  of  Chicago. 


10  ORGANIZATION  OF  COMMISSION 

The  Illinois  Society  of  Architects. 
The  Illinois  Chapter  of  the  American  Institute  of  Ar- 
chitects, and 

The  Western  Society  of  Engineers. 

THE  COMMISSION'S  WORKING  PRINCIPLE. 

The  Chicago  Commission  on  Ventilation  believes  that 
ventilation  must  become  an  applied  science  and,  therefore, 
conclusions  regarding  ventilation  must  be  open  to  revision 
in  the  light  of  experimental  evidence. 


The  Work  of  the  Commission 

Except  for  the  work  done  with  the  experimental  cab- 
inet, all  studies  and  tests  made  by  the  Commission  are  made 
in  rooms  or  buildings  of  full  size,  and  substantially  under 
normal  conditions  of  use.  Much  criticism  is  sometimes  of- 
fered against  conclusions  drawn  from  studies  made  with 
models  or  miniature  structures  usually  housed  within  a 
room.  If  such  criticism  be  just,  then  it  is  fortunate  that  our 
work  was  necessarily  done  in  enclosures  of  full  size  and 
built  in  accordance  with  various  architectural  designs. 

One  of  the  first  things  the  Commission  undertook  was 
to  make  a  general  study  of  the  ventilation  in  restaurants, 
cafes,  hotel  dining  rooms,  bakeries,  printing  offices,  office 
buildings,  and  other  places  in  which  health  might  be  im- 
paired because  of  the  lack  of  good  ventilation.  Some  of  the 
present  ordinances  in  the  city  code  are  based  upon  these 
studies. 

From  time  to  time,  the  work  has  become  more  definite 
and  intensive.  The  following  is  a  statement  of  the  main  line 
of  work  for  the  Commission  during  the  year  1913-14 : 

(1)  Tests  were  made  with  different  classes,  of  picture 
theater  buildings.    These  tests  were  made  with  the  buildings 
unoccupied.    It  was  planned  to  make  tests  of  an  occupied 
theater,  but  these  tests  were  necessarily  postponed. 

(2)  Tests  were  made  with  street  and  elevated  cars. 

(3)  Tests  with  the  experimental  cabinet  were  started. 

(4)  It  was  planned  to  make  some  tests  of  an  unoccu- 
pied church  building,  but  these  could  not  be  made  in  the 
time  which  the  Commission  had  at  its  disposal.    It  is  hoped, 
however,  that  within  the  coming  year  it  will  be  possible  to 
make  these  tests. 

Most  of  the  reports  which  follow  are  taken  from  the 
work  done  in  1913-14,  and  ^is^f airly  representative  of  what 
the  Commission  is  undertaking.  It  is  not  to  be  understood 
that  the  work  done  on  these  lines  is  completed.  The  field  is 
large  and  the  conditions  so  variable  that  much  remains  for 
the  future.  The  value  of  such  investigations  will  increase 
in  proportion  to  their  number. 


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fe     *n     n 

III 


Street  Car  Ventilation 

The  problems  involved  in  street  car  ventilation  must  be 
considered  under  two  distinct  headings : 

(1)  Those  relating  to  cars  used  for  interurban  trans- 
portation, such  as  day  coaches  and  sleepers ; 

(2)  Those  relating  to  cars  used  for  transportation 
within  the  city,  as  street  and  elevated  cars. 

In  the  former  class,  the  speed  is  relatively  high,  the 
stops  infrequent,  .and  the  proportion  of  air  space  to  passen- 
gers is  large.  With  cars  coming  under  this  classification, 
the  problem  of  ventilation  is  not  so  serious  as  with  the  lat- 
ter class. 

With  regard  to  street  and  elevated  cars  operating 
within  the  city,  these  conditions  are  reversed.  The  speed 
is  relatively  low,  the  stops  frequent,  and  the  air  space  per 
passenger  small;  consequently  the  air  leakage  observed  in 
cars  traveling  at  a  high  rate  of  speed  is  almost  entirely  ab- 
sent in  this  class.  Moreover,  the  leakage  is  further  reduced 
by  modern  methods  of  construction.  The  old  loose  window 
sashes  that  rattle  with  the  movement  of  the  car  and  the 
action  of  the  wind  have  been  replaced  by  metal  sash  and 
double  glass  construction,  and  arch-roofed  cars  are  being 
substituted  for  the  old  monitor  decks.  The  tendency  is  to 
make  these  cars  virtually  airtight  boxes  and  the  question  of 
ventilation  can  no  longer  be  left  to  chance. 

It  is  to  be  understood  in  discussing  the  ventilation  of 
street  and  elevated  cars  we  refer  only  to  the  operation  of 
such  cars  during  that  part  of  the  year  when  artificial  heat  is 
required.  At  such  time,  it  is  necessary  that  all  windows  be 
kept  closed  and  that  the  doors  remain  open  as  short  a  time 
as  possible. 

The  intramural  transportation  companies  of  Chicago 
are  operating  4,600  cars.  According  to  the  Fourth  Annual 
Eeport  of  the  Board  of  Supervising  Engineers,  for  the  year 
ending  January  31,  1911,  the  total  number  of  passengers 


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Street  Car  Ventilation.    Report  Form. 


STREET  CAR  VENTILATION  15 

carried  for  the  period  mentioned  is  853,785,689,  which  is 
over  2,340,000  per  day.  At  the  present  writing  these  figures 
can  safely  be  increased  15  per  cent. 

Considering  the  restricted  space  passengers  occupy  in 
surface  and  elevated  cars,  especially  at  the  rush  hours,  and 
the  consequent  intimate  contact  enforced,  the  necessity  for 
proper  ventilation  of  these  cars  becomes  apparent. 

Of  the  total  number  of  cars  in  service — 4,600 — 3,284  are 
operated  by  surface  line  companies,  and  1,431  by  the  ele- 
vated companies.  Of  the  surface  cars,  1,982  are  of  the  old 
monitor  deck  type,  ventilated  only  by  means  of  deck  sash 
windows;  250  are  equipped  with  so-called  automatic  ven- 
tilators, and  990  with  mechanical  exhaust  appliances. 

The  Commission  on  Ventilation  is  making  tests  of  the 
various  cars  in  service  to  determine  the  relative  efficiency 
of  the  different  systems  of  heating  and  ventilating,  and  to 
decide,  if  possible,  what  would  be  reasonable  requirements. 

TESTS. 

In  our  investigations  during  the  past  two  years,  we 
have  endeavored  to  determine  four  important  elements : 

(1)  Air  supply,  at  present  obtained  by  the  various 
methods  of  ventilation  employed : 

a — By  anemometer  readings, 
b — By  C02  analyses. 

(2)  Temperature  maintained  in  cars  in  service  during 
cold  weather. 

(3)  Dust: 

a — Amount, 
b — Character. 

(4)  Bacteria. 

METHOD  OF  MAKING  TESTS. 

In  determining  the  air  supply  in  mechanically  ventil- 
ated cars,  the  following  method  is  employed : 

In  one  type  of  installation  using  a  mechanical  exhaust, 
each  car  is  equipped  with  fourteen  outlet  registers  situated 
in  the  ceiling  of  the  car.  The  air  is  exhausted  through  these 


16  STREET  CAR  VENTILATION 

registers  into  an  air  space  between  the  head  lining  and  the 
roof,  by  means  of  a  10%-inch  cone  fan  driven  by  a  specially 
designed  direct  connected  motor.  By  means  of  a  galvan- 
ized iron  tube  six  inches  in  diameter,  fitted  with  a  coarse 
mesh  wire  screen  at  one  end  and  a  suitable  fastening  device 
at  the  other,  an  anemometer  is  suspended  at  each  register. 
Test  runs  are  made  in  every  direction,  covering  a  period 
of  from  two  to  eight  hours,  and  the  average  velocity  of  the 
air  through  each  register  is  determined.  The  velocity  in 
feet  per  minute  is  multiplied  by  the  area  in  square  feet  of 
the  opening  and  by  the  number  of  openings,  which  gives 
the  C.  F.  M.  exhausted.  The  results  obtained  in  this  man- 
ner are  checked  by  means  of  analyses  to  determine  the 
amount  of  of  carbon  dioxide  when  the  car  is  in  service. 

For  taking  air  samples,  an  ordinary  Paquelin  cautery 
bulb  with  about  sixteen  inches  of  rubber  tube  is  employed. 
Four  samples  are  usually  taken  at  a  time  in  an  occupied  car, 
in  the  same  manner  as  in  theaters  and  other  ventilation 
work.  (See  appendix.) 

Analyses  for  carbon  dioxide  are  made  to  determine  the 
amount  and  distribution  of  the  fresh  air  supply  and  not 
because  it  in  itself  is  considered  injurious  in  the  amounts 
found,  or  that  it  is  an  indication  of  other  organic  impuri- 
ties. 

In  cars  equipped  with  automatic  ventilators,  an  anem- 
ometer is  placed  in  each  outlet  opening.  In  the  cases  of 
ceiling  outlets,  the  method  used  is  the  same  as  just  de- 
scribed. Where  the  ventilators  have  been  installed  in  deck 
sash  openings,  the  anemometer  is  fastened  to  the  lower  rail 
of  the  deck  sash.  Tests  are  then  made  in  a  car  running  in 
every  direction  and  C02  analyses  made  as  a  check  on  the 
anemometer  readings.  In  cars  ventilated  only  by  deck  sash 
windows,  the  carbon  dioxide  anlyses  are  relied  upon  to  de- 
termine the  air  supply.  In  all  of  these  tests,  careful  obser- 
vations of  the  outside  weather  conditions  are  made,  the  tem- 
perature of  the  air,  direction  and  velocity  of  the  wind  hav- 
ing a  very  important  bearing  on  the  efficiency  of  the  ven- 
tilating equipment.  This  is  especially  true  of  the  auto- 
matic ventilators,  as  the  amount  of  air  exhausted  depends 


STREET  CAR  VENTILATION  17 

almost  entirely  on  the  speed  of  the  car  and  the  direction  and 
velocity  of  the  wind. 

TEMPERATURE. 

Temperature  observations  are  made  in  four  locations 
within  the  car,  at  the  waistline  of  seated  passengers. 

DUST. 

Dust  determinations  are  made  by  the  filter  method. 
For  this  work,  it  is  necessary  to  run  a  special  car  without 
passengers,  as  the  noise  of  the  machine  and  the  observa- 
tions necessary  would  seriously  interfere  with  the  comfort 
of  the  passengers.  These  tests  are  made  for  the  purpose 
of  determining  the  effects  of  various  intake  locations  on  the 
dust  content,  and  the  fact  that  the  car  is  unoccupied  is  of  no 
importance. 

BACTERIA. 

Quantitative  determinations  of  the  number  of  bacteria 
are  made  by  substituting  sand  for  sugar  in  the  filter  and 
plating,  incubating  and  counting  the  same  according  to  the 
method  described  in  the  appendix.  Eough  approximations 
of  the  quantitative  tests  are  made  by  exposing  standard 
Petrie  dishes  for  two  minutes  in  occupied  cars.  The  method 
of  recording  and  reporting  these  various  tests  and  observa- 
tions is  given  in  the  accompanying  charts  and  diagrams. 

(See  Charts,  pages  12  and  14.) 

DISCUSSION. 

These  observations  have  not  been  carried  on  for  a  suffi- 
cient length  of  time  to  warrant  the  commission  in  publishing 
conclusions.  We  feel,  however,  that  the  work  so  far  merits 
the  reporting  of  certain  pertinent  observations.  It  is  appar- 
ent from  the  work  done  that  the  method  of  ventilating  street 
and  elevated  cars  by  means  of  deck  sashes  is  very  unsatis- 
factory. In  cold  weather,  disagreeable  drafts  are  produced 
when  the  deck  sash  windows  are  open.  During  rain  or  snow 


18  STREET  CAR  VENTILATION 

storms  they  must  of  necessity  be  closed.  With  a  crowded 
car  when  this  method  of  ventilation  is  used,  repeated  tests 
have  demonstrated  that  the  air  supply  per  person  will  fall  as 
low  as  4  or  5  cubic  feet  per  minute.  This  condition  has  been 
apparent  for  some  time  to  the  public  and  to  persons  investi- 
gating the  question,  and  at  the  present  time,  the  transporta- 
tion companies  have  given  tacit  acknowledgment  to  the  fact, 
and  are  not  purchasing  or  building  cars  of  this  typ#.  The 
next  step  forward  was  the  substitution  of  the  so-called 
automatic  ventilators.  These  operate  on  the  principle  of 
the  ' '  T  "  tube,  and  depend  for  their  efficiency  on  the  speed  of 
the  car  and  the  direction  and  velocity  of  the  wind.  They 
have  some  features  to  recommend  them;  they  are  not  ex- 
pensive to  install  or  maintain,  and  are  always  in  operation. 
The  serious  objection,  however,  to  their  use  is  that  the  air 
supply  cannot  be  controlled,  since  it  depends  entirely  on 
the  velocity  at  which  the  outside  air  passes  through  the 
device.  When  cars  are  in  service  in  congested  districts,  they 
are  moving  slowly  and  make  frequent  stops.  They  are  also 
loaded  to  their  maximum  capacity.  This  is  the  time  when 
the  greatest  air  supply  is  required.  Owing,  however,  to  the 
slow  speed  and  frequent  stops,  the  automatic  ventilators 
are  operating  at  their  lowest  efficiency.  As  the  car  leaves 
the  congested  district  of  the  city,  the  number  of  passengers 
decreases,  the  stops  become  less  frequent,  and  the  speed 
becomes  higher.  The  automatic  ventilators,  at  this  time,  are 
working  at  their  maximum  efficiency,  but  at  a  time  when  the 
least  amount  of  air  is  required. 

The  mechanical  method  of  ventilation,  by  means  of 
plenum  or  exhaust  fans,  is  a  comparatively  new  proposition 
and  is  being  taken  up  by  the  transportation  companies  with 
reluctance.  Such  systems  are  more  expensive  than  the  auto- 
matic ventilators,  require  more  attention,  and  there  is  a 
slight  expense  for  operation  and  maintenance.  It  is,  how- 
ever, perfectly  apparent  that  up  to  this  time  an  adequate 
air  supply  properly  distributed  and  under  control  can  be 
obtained  in  no  other  way.  With  mechanical  ventilation  the 
amount  of  air  required  is  actually  supplied.  No  street  car 
yet  placed  in  service  in  the  city  of  Chicago  has  heating 
surface  of  capacity  sufficient  to  warm  this  amount  of  air. 


STREET  CAR  VENTILATION  19 

This  causes  the  real  objection  on  the  part  of  the  transporta- 
tion companies,  to  mechanically  ventilated  cars. 

While  the  mechanical  systems  at  present  in  use  are  open 
to  criticism  in  some  details,  we  feel  that  unless  great  im- 
provement is  made  in  natural  systems,  for  many  excellent 
reasons,  mechanically  ventilated  cars  should  be  required  in 
all  cities. 


Picture  Theater  Ventilation 

From  the  standpoint  of  methods  for  ventilation,  the 
picture  theaters  in  Chicago  fall  into  five  classes  or  types,  as 
follows : 

(1)  Unventilated. 

(2)  Ventilated  by  exhaust  fans  only,  without  definite 
provision  for  air  supply. 

(3)  Theaters  ventilated  by  exhaust  fans  at  one  end, 
with  suction  air  supply  through  tempering  coils  at  other 
end. 

(4)  Theaters  ventilated  by  supply  fans  forcing  air 
through  tempering  coils  at  one  end  and  exhausting  by  pres- 
sure at  the  other  end. 

(5)  Theaters  ventilated  by  supply  fans  forcing  air 
through  tempering  coils  and  special  distributing  ducts  and 
inlets,  exhausting  through  distributed  outlets  with  or  with- 
out fans,  temperature  control,  etc. 

During  the  winter  of  1913-14,  the  Commission  has  made 
tests  of  several  picture  theaters  in  the  city.  These  tests 
were  made  with  the  theaters  unoccupied.  The  aim  was  to 
determine  the  general  movement  of  air  within  the  theaters, 
and  this  could  be  done  quite  as  well  without  the  usual  picture 
theater  audience.  In  order  to  produce  convection  currents 
somewhat  similar  to  those  set  up  by  the  audience,  standard 
candles  were  placed  on  the  seats  and  lighted. 

Some  tests  were  made  with  a  candle  in  each  seat  and 
others  with  candles  in  alternate  seats.  The  purpose  in 
using  the  candles  in  the  latter  arrangement  was  to  produce 
approximately  the  same  amount  of  heat  and  C02  that  would 
be  produced  by  an  audience. 

The  candles  did  more  than  merely  to  furnish  convection 
currents  within  the  audience  chamber  as  may  be  noted  in 
the  following  reports  on  the  ventilation  of  typical  theaters 
under  classes  2,  3,  and  5.  If  the  convection  currents  were 
not  interfered  with  by  longitudinal  currents,  one  would  ex- 


PICTURE  THEATER  VENTILATION  21 

pect  the  maximum  content  of  carbon  dioxide  to  be  found  in 
the  upper  stratum  or  air.  The  facts,  however,  were  that  in 
general  the  maximum  carbon  dioxide  content  did  not  occur 
in  the  upper  stratum,  for  the  reason  that  longitudinal  air 
currents  were  found  especially  along  the  ceilings,  due  to  the 
general  method  of  air  introduction  and  removal. 

The  general  longitudinal  air  movements  were  studied 
by  means  of  clouds  of  ammonium  chloride  formed  from  the 
intermingling  of  gases  or  vapors  from  concentrated  ammo- 
nium hydroxide  and  concentrated  hydrochloric  acid. 

The  behavior  of  the  general  longitudinal  and  vertical 
currents  combined  was  studied  by  means  of  toy  balloons 
which  were  inflated  with  hydrogen  gas  and  counterpoised 
by  means  of  weights,  in  order  that  the  balloons  might  fol- 
low the  currents  in  wrhich  they  were  placed.  In  some  in- 
stances it  was  difficult  to  obtain  satisfactory  results,  be- 
cause of  the  very  great  difference  in  temperature  between 
the  incoming  air  and  that  which  had  been  in  the  room  for  a 
few  minutes.  This  condition  was  particularly  true  in  the- 
aters in  which  the  supply  of  air  for  ventilating  purposes  was 
brought  in  through  the  doors. 

It  is  only  in  the  construction  of  recent  picture  theater 
buildings  that  a  general  attempt  has  been  made  to  provide 
both  inlets  and  outlets  for  ventilation  purposes.  Except  in 
special  cases,  in  the  older  types  no  effort  was  made  to  pro- 
vide either  inlets  or  outlets. 

So  far  as  the  comfort  as  well  as  the  health  of  the  the- 
ater patrons  is  concerned,  there  needs  to  be  required  a 
better  connection  between  the  heating  and  the  ventilating 
of  picture  theater  buildings.  Specifically,  it  is  evident  from 
our  investigations  that  the  air  for  ventilation  purposes 
should  be  compelled  to  pass  through  heaters  before  it  comes 
in  contact  with  the  audience. 


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Test  of  Senate  Picture  Theater, 

736  W.  MADISON  STREET,  CHICAGO, 
February  21,  1914. 


See  Plans,  page  22. 


TYPE. 

The  theater  is  classified  under  Type  3  in  the  introduc- 
tion. The  fan  draws  air  through  vento  heaters  and  forces  it 
into  the  room.  The  air  finds  its  way  out  through  doors  and 
windows,  no  special  outlet  being  provided. 

SEATING  CAPACITY. 
Seats  are  provided  for  three  hundred. 

SYSTEM  OF  HEATING. 

Low  pressure  gravity  steam.  Theater  is  supplied  with 
five  (5)  100  square  foot  direct  radiators,  with  300  square 
feet  of  vento  for  tempering  the  air. 

SYSTEM  OF  VENTILATION. 

Supplied  by  dilution  under  fan  pressure,  the  fresh  air 
diluting  and  displacing  vitiated  air,  the  latter  escaping  from 
the  auditorium  through  the  lobby  and  entrance  doors.  It  is 
possible  to  keep  these  doors  open  on  account  of  the  extreme 
length  of  the  lobby. 

INTAKE. 

Thirty-six-inch,  circular,  through  roof  fourteen  feet 
above  alley  grade. 


24  PICTURE  THEATER  VENTILATION 

SUPPLY  FAN. 

One  full  housed  steel  plate  blower  with  a  wheel  forty- 
two  inches  in  diameter,  speed  350  R.  P.  M.,  delivering  6,000 
cubic  feet  of  air  per  minute. 

INLET  OPENINGS. 

Two  grilles  about  nine  feet  above  the  floor  at  front  end 
of  theater. 

EXHAUST  FANS. 
None  provided. 

OUTLET  OPENINGS. 

No  special  provision  is  made  for  outlets  on  account  of 
the  peculiar  construction  of  the  building,  the  entrance  doors 
being  continuously  open  and  serving  this  purpose. 

DISCHARGE  OPENINGS. 
None  provided. 

HEATER. 

Consists  of  three  stacks  of  regular  forty-inch  vento, 
nine  sections  to  each  stack.  At  the  time  of  the  test  the  coils 
were  not  operating  properly,  owing  to  some  trouble  with  the 
air  valves  or  other  connections. 

TEST — WITH  FAN  RUN  NING. 

( a )  Time— 9 :45  to  11 :30  a.  m. 

(b)  Temperature — Outside    was    plus    28    deg.    F. 
throughout  test.    One  hundred  and  fifty  standard  candles, 
corresponding  closely  in  heat  output  to  300  occupants,  were 
evenly  distributed  on  the  seats  throughout  the  auditorium, 
one  candle  being  placed  on  each  alternate  seat.     These 


PICTURE  THEATER  VENTILATION 


25 


heated  the  theater  from  plus  60  deg.  F.  to  plus  80  deg.  F.  in 
a  very  short  time.  The  temperature  was  very  rapidly  low- 
ered as  soon  as  the  fan  was  turned  on.  (See  chart  on 
plate  3.) 

(c)  C02  Test — Samples  were  taken  as  marked  on  the 
plans  at  levels  of  1,  5,  and  9  feet  above  the  floor  in  each 
location.  The  sample  bulb  was  broken  after  two  sets  of 
samples  had  been  collected ;  analyses  of  these  samples,  how- 
ever, gave  an  average  of  7.1,  8.8,  and  8.2  parts  of  C02  at  the 
levels  previously  mentioned. 


Thermometer  Readings. 

Fan  not  Running 

Fan  Running 

No. 

9.45 

10.00 

10.25 

10.40 

Out- 
side 

A-l 

nVz 

80 

Q91A 

67 

28° 

1-2 

73 

82K 

69 

67 

28° 

A-6 

69^ 

78^ 

62^ 

62 

28° 

1-6 

69M 

77^ 

62 

62 

28° 

A-l  6 

69^ 

76 

56 

59^ 

28° 

1-16 

69J/2 

78 

5iy2 

60 

28° 

(d)  Ammonium  Chloride  Test — The  ammonium  chlo- 
ride was  liberated  at  the  inlet  openings.    It  traveled  the 
length  of  the  room  in  one  and  a  half  minutes.    With  the 
doors  open  and  the  fan  running  the  air  became  clear  in  ten 
minutes. 

(e)  Bacteria,  Relative  Humidity,  and  Dust — No  tests 
to  determine  the  number  of  bacteria,  the  relative  humidity, 
or  the  number  of  dust  particles  were  made. 

(f)  Balloon  Test — Standard  balloons  were  liberated 
at  the  inlet  openings.    The  course  taken  by  these  balloons 
indicated  that  a  part  of  the  fresh  air  currents  struck  the 
projecting  operator's  room,  turned  upward  and  returned 
along  the  ceiling  towards  the  point  of  air  introduction. 
Other  balloons  passed  underneath  this  projection  and  trav- 
eled to  the  rear  of  the  theater,  indicating  that  probably 
three-quarters  of  the  air  supply  followed  this  course,  trav- 
eling the  length  of  the  auditorium,  thence  into  the  lobby  and 
out  the  exit  doors.    When  the  entrance  doors  were  closed 
some  of  the  balloons  passed  backward  from  the  inlet  open- 
ings to  the  projecting  operator's  booth  and  from  this  point 


2«  PICTl'RE  THEATER  VENTILATION 

descended  directly  to  the  floor  line,  where  they  remained 
with  very  little  movement.  When  the  doors  were  opened, 
however,  these  balloons  passed  backward  to  the  rear  of  the 
theater  with  a  slow  and  uniform  velocity. 

DISCUSSION. 

The  rapid  rise  of  temperature,  due  to  occupants  (can- 
dles) is  striking.  It  is  also  evident,  from  the  quick  drop  in 
temperature  when  the  fan  was  started,  that  untempered  air 
cannot  be  introduced  into  a  theater  in  cold  weather,  for  de- 
spite the  fact  that  the  direct  radiators  were  all  hot,  the  tem- 
perature fell  from  80  deg.  when  the  fan  was  started  to  from 
51  deg.  to  69  deg.,  depending  upon  where  the  observations 
were  made,  in  twenty-five  minutes.  This  was  undoubtedly 
due  to  the  fact  that  the  tempering  coils  were  air  bound  and 
inoperative.  The  operator's  room  is  located  in  a  peculiar 
manner,  being  about  midway  between  the  front  and  rear 
of  the  theater  and  projecting  downward  within  ten  feet  of 
the  floor.  (See  plan.)  The  situation  of  the  operator's  room, 
as  described,  has  the  effect  of  breaking  up  the  air  currents 
from  the  inlets  and  makes  it  rather  difficult  to  obtain  proper 
air  distribution.  The  analyses  of  the  air  samples  and  the 
behavior  of  the  balloons,  together  with  the  ammonium  chlo- 
ride test,  indicate  that  the  air  currents  at  the  front  of  the 
theater  are  broken  up  at  the  operator's  booth.  Back  of  this 
point  the  air  currents  are  hardly  noticeable,  but  the  air  sup- 
ply and  distribution  are  good. 

DEDUCTIONS. 

The  drop  in  temperature  when  the  fan  was  in  operation 
emphasizes  the  fact  that  proper  installation  and  operation 
of  tempering  coils  is  imperative.  It  is  also  necessary  that 
provisions  be  made  properly  to  control  the  temperature  of 
the  incoming  air.  There  must  be  provided  adequate  means 
of  air  discharge,  usually  independent  of  the  doors  or  win- 
dows. In  this  instance,  however,  the  peculiar  construction 
of  the  building,  viz. :  the  long  lobby,  makes  it  possible  to 
utilize  the  entrance  doors  to  advantage. 


Test  of  Austin  Picture  Theater, 

5619  W.  MADISON  STREET,  CHICAGO,  ILL. 
BY  THE  CHICAGO  COMMISSION  ON  VENTILATION, 

March  7,  1914. 


See  Plans,  pages  28  and  29. 


TYPE. 

This  theater  is  classified  under  Type  5  in  the  introduc- 
tion. The  fan  forces  air  through  a  heater  and  the  ducts, 
and  into  the  room  by  distributed  floor  inlets.  The  air  is 
driven  out  through  openings  in  the  ceiling  by  the  fan  pres- 
sure. 

SEATING  CAPACITY. 

Five  hundred  and  thirty-three. 

SYSTEM  OF  HEATING. 

Furnace  plenum  system.  The  furnace  is  under  the 
highest  part  of  the  sloping  floor.  The  heated  air  must  be 
driven  down  the  inclined  masonry  ducts,  against  its  natural 
tendency  to  rise,  a  distance  of  about  75  feet  to  drainage 
point,  thence  through  balance  of  duct  50  feet  with  a  slight 
upward  incline.  The  ducts  contained  from  one-half  to  two 
inches  of  ice  and  water  at  drainage  points.  This  had  accumu- 
lated, as  the  building  had  not  been  in  use  or  heated  for  sev- 
eral months  previous  to  test.  There  are  no  direct  radiators. 
The  building  can  be  heated  only  when  the  fan  is  in  opera- 
tion. There  is  danger  of  overheating  and  resultant  injury 
to  the  furnace  if  the  fan  is  not  operated  when  the  furnace  is 
fired. 

SYSTEM  OF  VENTILATION. 

By  displacement  under  fan  pressure.  The  incoming  air 
is  introduced  into  the  theater  through  105  six-inch  mush- 


30  PICTURE  THEATER  VENTILATION 

room  inlet  openings  distributed  under  the  seats  of  the  the- 
ater and  the  air  escapes  through  outlets  in  the  ceiling. 

INTAKE. 

From  a  point  three  feet  above  the  roof  line  2x5  feet  in 
size. 

SUPPLY  PAN. 

One  full  housed  steel  plate  blower  with  wheel  48  inches 
in  diameter,  378  R.  P.  M.,  delivering  15,000  C.  F.  M. 

INLET  OPENINGS. 

One  hundred  and  five  in  number,  six  inches  in  diameter, 
capped  with  adjustable  mushroom  deflectors. 

OUTLET  OPENINGS. 
Four,  30-inch  in  diameter,  located  in  the  ceiling. 

EXHAUST  FAN. 
None  provided. 

DISCHARGE  OPENINGS. 
Same  as  outlet  openings. 

HEATER, 

One  No.  80  Harrison  air  tube  furnace.  This  is  a  coal 
burning  firebox  below  a  series  of  horizontal  iron  tubes, 
through  which  the  air  is  forced  by  the  fan.  The  heater  con- 
tains 64  four-inch  tubes. 

TEST — WITH  FAN  RUNNING. 
(a)     Time— 11 :30  a.  m.  to  1 :30  p.  m. 


PICTURE  THEATER  VENTILATION 


31 


(b)  Temperature — The  outside  temperature  was  plus 
33  deg.  F.  throughout  the  test.     Two  hundred  and  sixty 
standard  candles,  corresponding  nearly  in  heat  output  to 
533  occupants,  were  distributed  on  alternate  seats.    Tem- 
peratures noted  at  various  times  and  at  different  points  are 
indicated  on  the  plans.     Thermometer  stations  shown  by 
"T"  were  five  feet  above  the  floor.    Thermometer  stations 
in  the  supply  ducts  are  shown  by  1-2-3,  etc.    The  tempera- 
ture of  heated  air  at  the  furnace  was  in  excess  of  plus  210 
deg.  F.,  the  limit  of  the  thermometer.    It  was  probably  as 
high  as  400  deg.  F.    The  tubes  of  the  furnace  became  red 
hot,  as  did  the  breeching. 

(c)  C02  Tests— Samples  were  taken  at  "A,"  "B," 
"C,"  etc.,  marked  on  the  plans,  at  levels  1,  5,  and  9  feet 
above  the  floor.     These  samples  were  unsatisfactory,  due 
to  some  mistake  in  technique. 


Station 

11.53 
A.M. 

12.25 
P.M. 

12.55 
P.M. 

1.15 
P.M. 

1.30 
P.M. 

1.45 
P.M. 

Air  Vel. 

Duct  Stations 

1 

40 

54 

60 

63 

65 

72 

580 

2 

39 

54 

65 

69 

70 

72 

464 

3 

38 

55 

61 

67 

67 

64 

430 

4 

39 

84 

100 

103 

111 

111 

650 

5 

39 

111 

128 

135 

141 

144 

770 

6 

39 

110 

130 

138 

140 

142 

820 

7 

39 

108 

124 

130 

138 

142 

830 

[House  Stations 

A 

36 

46 

52 

58 

61 

63 

B 

37 

50 

56 

63 

66 

67 

C 

37 

54 

58 

64 

67 

68^ 

D 

37 

54 

58 

65^ 

68 

70   I 

E 

39 

56 

64 

71 

74 

76 

F 

38 

56 

64 

74 

74 

77 

(d)  No  ammonium  chloride  test  was  made. 

(e)  Bacteria,  Relative  Humidity,  and  Dust — Tests  to 
determine  the  number  of  bacteria,  the  number  of  dust  par- 
ticles, and  the  relative  humidity  were  not  made. 

(f)  Balloon  Test — The  standard  balloons  were  lib- 
erated at  various  points  in  the  theater;  first,  at  about  four 
feet  above  the  floor,  along  the  front  row  of  seats  nearest  the 
stage.    These  balloons  took  a  uniform  course  backward  over 
the  tops  of  the  seats,  moving  at  a  very  slow  velocity.    They 
would  usually  gain  a  position  in  the  aisle  and  pass  back- 
ward to  the  low  point  of  the  auditorium   at   about  40 


32  PICTURE  THEATER  VENTILATION 

feet  from  the  stage.  Here  they  would  rise  vertically  to 
within  three  or  four  feet  of  the  ceiling,  pass  forward  to 
the  stage  and  down  again  to  the  point  where  liberated.  One 
balloon,  it  was  noted,  made  this  excursion  six  times.  At  the 
end  of  the  sixth  circuit,  it  escaped  into  the  large  ceiling  vent. 
Some  of  the  balloons,  if  they  succeeded  in  passing  this  cen- 
tral point  in  the  theater,  traveled  backward  toward  the  rear 
at  a  uniform  low  velocity,  showing  a  continuous  preference 
for  the  aisles. 

(g)  Anemometer  Test — Anemometer  readings  are 
marked  on  the  plans.  The  mushroom  deflectors  were  re- 
moved for  temperature  and  anemometer  readings  No.  1  to 
No.  7. 

DISCUSSION. 

The  theater  is  architecturally  handsome,  but  the  con- 
struction and  arrangement  of  its  heating  plant  is  unfortu- 
nate. The  roof  slab  forms  the  ceiling  without  any  insulat- 
ing space.  The  distributing  ducts  are  wet,  rough,  and  in- 
cline downward  from  the  furnace  to  the  central  point,  and 
then  slightly  upward  to  the  stage  end  of  the  theater.  Ap- 
parently no  attempt  had  been  made  previous  to  test  to 
equalize  the  air  distribution  by  means  of  proper  adjustment 
of  mushrooms.  After  three  hours  of  continuous  operation, 
in  order  to  maintain  a  temperature  of  plus  64  deg.  at  the  end 
of  the  theater  nearest  the  stage,  which  is  farthest  situated 
from  the  heating  plant,  the  end  nearest  the  heater  was 
warmed  to  plus  80  deg.  F.  The  owner  evidently  intended 
to  secure  a  high-grade  ventilating  system,  which  embodied 
provision  for  reasonable  air  distribution  and  a  uniform  tem- 
perature. The  cold  ceiling,  the  wet  ducts,  and  the  improper 
location  of  the  heater  all  combine  to  defeat  this  end. 

DEDUCTIONS. 

An  underground  masonry  duct  must  at  all  times  be  dry. 
The  ducts  must  be  well  proportioned.  In  systems  of  this 
type,  they  should  not  run  downward  from  the  heater,  owing 
to  the  inherent  difficulties  in  heat  distribution.  They  must 
be  carefully  tested  and  the  delivered  air  must  be  thoroughly 


PICTURE  THEATER  VENTILATION  33 

equalized.  When  starting  the  heating  plant  in  a  cold  the- 
ater, equipped  with  masonry  ducts,  sufficient  time  must  be 
given  to  warm  the  ducts  thoroughly.  It  is  improper  for 
ventilating  purposes  to  heat  even  a  small  quantity  of  air  to 
a  high  temperature.  The  air  supply  should  be  large  in  vol- 
ume and  comparatively  low  in  temperature  if  good  results 
are  to  be  obtained.  The  ducts  must  never  be  heated  to  such 
extent  that  the  introduction  of  air  at  a  temperature  lower 
than  the  air  in  the  room  is  prevented.  The  incoming  air 
must  be  cooler  than  the  air  in  the  room  to  prevent  an^excess 
temperature  when  a  large  percentage  of  seats  is  occupied. 
Some  local  means  of  heating  at  the  end  farthest  from  the 
heating  plant  seems  desirable.  Such  wide  variation  of 
temperatures  as  were  found  here  is  most  objectionable. 
There  should  be  simple  and  efficient  mixing  dampers  at  the 
furnace  so  that  part  or  all  of  the  air  may  be  by-passed 
around  the  heater  as  requirements  indicate.  Perfect  drain- 
age of  ducts  is  of  vital  importance. 


Test  of  Bell  Picture  Theater, 

2407  W.  MADISON  STKEET,  CHICAGO,  ILL. 
January  10,  1914. 


See  Plans,  page  35. 

TYPE. 

This  theater  is  classified  under  Type  2  in  the  introduc- 
tion. Exhaust  fans  draw  the  air  out.  It  is  supposed  to 
enter  through  doors  and  windows  and  two  openings  pro- 
vided at  the  floor  line  in  the  opposite  end  of  the  theater. 

SEATING  CAPACITY. 
Three  hundred  and  fifty. 

SYSTEM  OF  HEATING. 
Low  pressure  gravity  steam  with  direct  radiators. 

SYSTEM  OF  VENTILATION. 

Exhaust,  by  dilution.  No  special  provision  has  been 
made  for  heating  the  entering  air. 

INTAKE. 

No  special  provisions  made  for  intake.  Air  must  gain 
entrance  through  lobby  doors.  Two  20x36-inch  openings  in 
the  floor  at  the  rear  of  theater,  allowing  some  air  to  enter 
from  the  lobby. 

OUTLET  OPENINGS. 
Directly  to  fan  placed  in  the  rear  wall. 


IF 


IB 


«r   trt4lb,*J0  ~S 
I»99*S  rfrzf' 


M  PIC  TURK  THEATER  VENTILATION 

EXHAUST  FANS. 

Two  24-inch  propeller  type  fans  situated  in  the  front 
wall  of  the  theater,  one  on  either  side  of  the  stage ;  capacity, 
about  4,000  C.  F.  M.  each. 

DISCHARGE  OPENINGS. 

Two  36-inch  roof  ventilators  are  provided.  These  were 
closed  at  the  time  of  test.  The  fans  discharge  directly  to  the 
outer  air. 

HEATER. 

TEST — WITH  FANS  RUNNING. 

(a)  Time— 11 :30  a.  m.  to  1 :00  p.  m. 

(b)  Temperature — The  outside  temperature  was  plus 
27  deg.  F.    One  hundred  and  seventy-five  standard  candles, 
corresponding  nearly  in  heat  output  to  350  occupants,  were 
distributed  throughout  the  theater,  one  being  placed  in 
each  alternate  seat.    The  various  temperatures  noted  are 
marked  on  the  plans.    The  direct  radiators  were  hot. 

(c)  C02  Test — Samples  of  air  were  taken  at  points 
one-third,  one-half,  and  two-thirds  of  the  distance  from  the 
entrance  to  the  stage  of  the  theater,  at  levels  of  1,  5,  and  9 
feet  from  the  floor.    The  averages  at  the  one-foot  level  were 
7.2 ;  at  the  five-foot  level  7.3 ;  and  at  the  nine-foot  level  6.9 
parts  of  C02  per  10,000  parts  of  air. 

(d)  Ammonium  Chloride  Test — This  was  made  with 
the  doors  open  and  both  fans  operating.    It  required  ten 
minutes  to  clear  the  air  in  the  room. 

(e)  Ammonia  Test — Standard  Shepherd  phenolphtha- 
lein  cartridges  were  placed  as  marked  on  the  plans  about 
five  feet  from  the  floor.    Ammonia  was  introduced  at  the 
entrance.    The  cartridges  showed  no  reaction. 

(f )  Bacteria,  Eelative  Humidity,  and  Dust — No  tests 
to  determine  the  number  of  bacteria  or  of  dust  particles,  and 
no  relative  humiditv  observations  were  made. 


PICTURE  THEATER  VENTILATION  37 

(g)  Balloon  Test — Standard  balloons  were  released: 
No.  1  from  an  open  door.  This  passed  along  the  floor,  down 
the  aisle,  and  stopped  after  traveling  half  way  to  the  stage. 
No.  2  traveled  the  entire  length  of  the  theater  at  the  floor 
line  in  the  aisle  in  thirty  seconds.  No.  3  followed  the  course 
of  No.  1  to  the  center,  then  rose  to  the  ceiling  and  moved 
slowly  towards  fan  "  L, "  stopping  permanently  about  thir- 
ty-five feet  from  the  fan  at  the  ceiling.  No.  4  and  several 
others  were  released  near  the  entrance  doors  when  the  lat- 
ter were  closed.  The  balloons  moved  very  slowly,  some- 
times in  the  aisles  and  sometimes  under  the  seats,  to  about 
the  center  of  the  theater ;  they  remained  at  the  floor  line. 
No.  5  and  several  others  were  released  in  the  center  of  the 
length  of  the  theater  at  the  sides,  with  the  doors  open.  They 
moved  toward  the  exit  end  about  twenty  feet  and  stopped  at 
the  floor. 

DISCUSSION. 

In  order  to  ventilate  this  theater  to  any  appreciable 
extent,  it  was  necessary  for  the  entrance  doors  to  be  open. 
The  theater  could  not  be  heated  with  the  doors  open.  The 
air  movement  was  sluggish  when  the  doors  were  closed. 
With  the  candles  and  radiators  in  operation,  the  tempera- 
ture rose  to  only  plus  61  deg.  F.,  when  the  outside  tempera- 
ture was  plus  27  deg.  F.  Evidently  the  room  cannot  be 
heated  adequately  in  zero  weather  with  the  fans  operating. 
The  incoming  fresh  air  if  cold  tends  to  create  drafts  along 
the  floor,  as  indicated  by  the  balloon  tests.  This  incoming 
air,  if  at  a  low  temperature,  travels  at  the  floor  line  until  it 
has  passed  about  half  the  length  of  the  theater,  when  it  be- 
comes broken  up  and  mixed  with  warm  inside  air.  From 
here  it  rises  and  takes  a  more  or  less  direct  course  toward 
the  exhaust  fans. 

Another  interesting  observation  was  that  the  air  cur- 
rents, as  indicated  by  the  balloons,  tended  to  follow  closely 
and  be  confined  to  the  limits  of  the  aisles. 

The  analyses  of  the  air  samples  indicate  that  about 
1,500  cubic  feet  of  air  were  being  supplied  per  person  per 
hour  in  the  breathing  zone. 


38  PICTURE  THEATER  VENTILATION 

DEDUCTIONS. 

It  is  necessary  that  adequate  air  inlets  properly  located 
be  provided.  Provision  must  also  be  made  for  properly 
regulating  the  temperature  of  the  incoming  air.  No  ventila- 
tion of  any  value  is  in  effect  when  the  doors  are  closed, 
cold  drafts,  as  well  as  operative  conditions,  militate  against 
the  doors  being  left  open  continuously  in  cold  weather. 

In  systems  of  this  type,  it  is  very  important  that  the 
temperature  of  the  incoming  air  be  controlled,  as  the  cold 
air  will  follow  the  floor  and  create  objectionable  drafts.  If 
the  air  is  too  warm,  it  will  rise  to  the  ceiling  and  pass  over 
the  breathing  zone. 


An  Experiment  in  Ventilating 
^  a  School  Room 

One  of  the  first  experiments  determined  upon  by  the 
Chicago  Commission  on  Ventilation  pertained  to  the  ventil- 
ation of  a  schoolroom.  For  a  long  time  many  of  the  teach- 
ers of  the  public  schools  of  Chicago  complained  of  the  ven- 
tilation within  their  rooms.  Therefore,  with  the  hearty 
approval  and  co-operation  of  the  Board  of  Education,  the 
experimental  work  was  undertaken  in  the  autumn  of  1910. 
The  attitude  of  the  Board  of  Education  has  always  been  to 
improve  the  present  system  of  mechanical  ventilation  within 
our  public  schools,  if  possible.  All  expenses  in  connection 
with  the  experiments  on  schoolroom  ventilation  are  gladly 
borne  by  the  Board  of  Education. 

The  public  school  buildings  of  Chicago  are  equipped 
with  the  plenum  system,  operating  at  a  pressure  of  approxi- 
mately one-half  ounce. 

PLACE  OF  EXPEBIMENT. 

The  Chicago  Normal  College,  Sixty-eighth  street  and 
Stewart  avenue,  Chicago. 

TIME  OF  EXPERIMENT. 

The  experimental  work  has  continued  from  the  autumn 
of  1910. 

QUANTITY  OF  AIR. 

The  first  tests  made  were  somewhat  in  the  nature  of 
checking  up  the  worfc  of  the  builders.  A  rule  of  the  Board 
of  Education  requires  the  delivering  of  a  minimum  of  1,800 
cubic  feet  of  air  per  pupil  per  hour.  Anemometer  readings 
made  in  several  of  the  rooms  of  the  Normal  College  showed 
thru  it  was  being  delivered.  There  remained, 


40  VENTILATING  A  SCHOOL  ROOM 

however,  a  closely  related  question :  namely,  whether  or  not 
each  pupil  is  supplied  with  his  share. 

DISTRIBUTION  OF  AIR.  ^ 

Studies  were  made  for  air  currents  in  two  classrooms 
and  one  laboratory  room. 

DEVICES  USED. 

The  tests  for  air  currents  were  made  by  the  use  of  toy 
balloons  which  were  inflated  with  hydrogen  gas  and  coun- 
terpoised in  the  rooms  by  means  of  improvised  weights.  In 
addition  to  the  toy  balloons,  small  turbine  wheels  were  used. 
These  were  made  from  aluminum,  cork,  and  steel  needles, 
and  were  especially  constructed  for  these  tests.  The  blades 
of  the  turbines  were  made  from  aluminum  and  set  into  hubs 
of  cork.  Across  one  end  of  a  cork  hub  and  parallel  with  the 
plane  of  the  blades,  was  fastened  a  strip  of  aluminum  con- 
taining a  slight  indentation  in  which  the  pivot  of  the  device 
turned.  The  fine  point  of  a  steel  needle  served  as  a  pivot, 
and  when  ready  for  use  the  turbine  revolved  in  a  horizontal 
plane.  These  turbines  are  very  sensitive  to  vertical  cur- 
rents of  air — in  fact,  they  respond  to  convection  currents 
from  the  heat  of  one's  hand.  The  counterpoised  balloons 
were  useful  in  tracing  all  air  currents,  irrespective  of  their 
direction,  whereas  the  turbine  wheels  could  be  used  only  in 
testing  for  vertical  currents. 

TESTS  FOR  AIR  CURRENTS. 

One  of  the  classrooms  tested  is  25  by  25  feet  and  has  an 
east  exposure.  The  other  walls  of  the  room  have  no  imme- 
diate contact  with  the  outdoors.  The  inlet  and  outlet  ducts 
in  this  room  are  installed  in  the  north  wall,  and  the  air  en- 
ters the  room  with  a  velocity  of  about  650  feet  per  minute. 
When  balloons  were  pushed  into  the  entering  currents,  they 
were  hurried  across  the  room  near  the  ceiling  to  the  south 
wall.  From  the  ceiling  at  the  south  wall,  the  balloons  usu- 
ally took  one  of  two  general  courses,  depending  largely  upon 


VENTILATING  A  SCHOOL  ROOM  41 

outdoor  weather  conditions.  If  the  outdoor  temperature 
was  low  and  the  wind  was  blowing  directly  against  the  win- 
dows, then  the  balloons  moved  over  to  the  outside  wall, 
down  the  wall  or  windows,  and  over  to  the  outlet  duct.  If 
the  outside  temperature  was  moderate,  then  instead  of  the 
balloons  crossing  over  to  the  outside  wall,  they  were  likely 
to  poise  in  the  southeast  corner  of  the  room,  or  possibly 
move  vertically  down  along  the  wall  opposite  the  inlet  duct 
to  within  a  foot  or  two  of  the  floor,  and  then  over  to  the 
outlet  duct.  It  was  very  noticeable  that  air  currents  estab- 
lished themselves  in  aisles  and  other  open  spaces  along  the 
floor.  During  the  winter  season  the  turbine  wheels,  when 
placed  on  the  window  ledges,  revolved  almost  all  the  time. 
Their  direction  of  rotation  indicated  the  downward  move- 
ment of  a  sheet  of  cold  air ;  moreover,  this  sheet  of  cold  air 
was  very  perceptible  to  any  one  seated  near  the  outside 
wall  or  windows. 

The  other  classroom  is  26  by  45  feet;  is  a  northwest 
corner  room.  It  has  about  twice  as  much  exposure  on  the 
north  as  on  the  west  side.  As  already  stated,  there  are  two 
inlets  and  two  outlets  in  this  room,  and  they  are  located  in 
the  long  inside  wall.  The  velocity  of  the  incoming  current 
of  air  was  practically  the  same  as  in  the  smaller  room. 
Anemometer  readings  showed  an  adequate  supply  of  air 
for  good  ventilation.  Balloons  placed  in  the  incoming  cur- 
rent were  hurried  across  the  room  to  the  opposite  wall,  the 
outside  wall  with  the  north  exposure.  After  reaching  the 
outside  wall,  they  almost  always  went  vertically  downward 
to  within  a  foot  or  two  of  the  floor ;  then  they  moved  over  to 
the  outlets  near  the  floor  and  almost  directly  under  the  in- 
lets. The  hot  incoming  air  driven  against  the  cold  outside 
north  wall  and  windows,  reduced  the  influence  of  wall  and 
window  chill.  But  in  cold  weather,  especially  with  a  north 
or  northwest  wind,  a  downward  moving  sheet  of  cold  air 
was  very  noticeable.  The  small  turbine  wheels  revolved 
constantly  in  cold  weather  when  placed  upon  the  window 
ledges  or  near  the  exposed  walls.  In  the  central  part  of  the 
room,  that  is,  between  the  two  sets  of  inlet  and  outlet  ducts, 
the  balloons  did  not  show  perceptible  air  currents.  Fur- 


42  VENTILATING  A  SCHOOL  ROOM 

thermore,  there  seemed  to  be  eddies  in  close  proximity  to 
the  currents  at  either  end  of  the  room. 

The  laboratory  room  in  which  the  tests  for  air  currents 
was  made  is  26  by  45  feet,  and  is  a  northeast  corner  room. 
It  has  about  twice  as  much  exposure  on  the  north  as  on  the 
east  side.  The  room  has  two  inlets  and  two  outlets  on  the 
long  inside  wall.  The  inlet  duct  at  the  west  end  of  the  room 
is  so  close  to  the  west  wall  and  ceiling  that  when  the  current 
of  air  is  delivered  against  the  north  or  outside  wall,  it  takes 
a  diagonal  course  downward  and  inward  along  the  north 
wall,  and  across  the  windows.  By  this  action  of  the  air  cur- 
rent shown  by  balloon  tests,  there  is  a  considerable  section 
of  the  west  end  of  the  room  in  which  no  perceptible  air  cur- 
rents can  be  found.  At  the  east  end  of  the  room,  the  air 
current  behaves  as  might  be  expected,  namely,  the  incoming 
air  crosses  from  the  south  to  the  north  end  of  the  room 
along  the  ceiling,  strikes  the  cold  outside  wall  and  windows, 
drops  vertically  downward,  and  moves  over  to  the  outlet. 
Turbine  wheels  placed  near  the  windows  or  outside  wall 
during  cold  weather  were  constantly  rotating.  The  direc- 
tion of  rotation  indicated  a  downward  current  of  air. 

CONCLUSION. 

From  the  evidence  obtained  in  the  use  of  the  balloons 
and  turbine  wheels,  it  is  fair  to  conclude  that  air  within  the 
schoolrooms  tested  did  not  act  as  anticipated  in  the  plenum 
system.  Moreover,  the  action  of  the  balloons  and  turbine 
wheels  under  varying  weather  conditions,  especially  as  re- 
gards direction  and  velocity  of  winds,  warrants  the  conclu- 
sion that  in  the  type  of  construction  with  which  we  were 
concerned,  air  distribution  is  seriously  interfered  with  by 
conditions  for  which  the  plenum  system,  as  generally  in- 
stalled, is  not  responsible. 

THE  EXPERIMENTAL  ROOM. 

The  first  constructive  effort  in  the  ventilation  of  a 
schoolroom  in  which  the  plenum  system  had  been  installed 
was  made  in  one  of  the  regular  schoolrooms  of  the  Chicago 


VENTILATING  A  SCHOOL  ROOM  43 

Normal  College.  The  schoolroom  was  fitted  up  as  an  ex- 
perimental room.  One  of  the  factors  considered  in  the 
selection  of  the  experimental  room  was  that  of  subjecting 
it  to  our  northwest  winter  winds. 

The  experimental  room  is  24  by  32  feet,  on  the  basement 
floor,  and  has  a  west  exposure.  The  room  originally  had  a 
thirteen-foot  ceiling.  In  the  original  installation  for  ven- 
tilation, air  entered  the  room  near  the  ceiling  at  the  center 
of  the  east  wall.  The  main  air  current  was  across  the  room 
from  the  east  wall  to  the  west  (outside)  wall,  then  down  the 
cold  outside  wall,  and  back  to  the  outlet  duct  near  the  floor 
in  the  east  wall.  The  changes  made  in  the  room  were  as  fol- 
lows: First,  the  outlet  duct,  near  the  floor,  was  closed; 
then  an  airtight  false  floor  was  built  about  eighteen  inches 
above  the  regular  floor  of  the  room,  and  a  false  ceiling  was 
hung  about  eight  inches  below  the  room  ceiling;  then  an  air 
shaft  was  constructed  to  connect  the  inlet  duct  of  the  orig- 
inal installation  with  the  air  reservoir  between  the  floors. 

(See  Plates  1  and  2,  pages  85  and  86.) 

Outlet  duct  was  tapped  near  the  ceiling  connecting  it 
with  the  compartment  between  the  ceiling  and  the  false 
ceiling.  Three-inch  circular  holes  were  cut  through  the 
false  floor,  and  galvanized  iron  pipes,  fitted  into  these  open- 
ings, led  under  each  desk  to  within  an  inch  of  the  desk  bot- 
tom. Openings  also  were  made  through  the  false  ceiling  so 
that  air  delivered  into  the  room  might  move  on  through  it. 
It  will  be  noted  that  these  changes  turned  the  operation  of 
the  plenum  system  upside  down.  Instead  of  the  air  enter- 
ing at  the  ceiling  and  leaving  near  the  floor  line,  this  new 
scheme  delivered  the  air  below  the  floor,  and  outgoing  cur- 
rents left  the  room  at  the  ceiling.  As  already  intimated,  the 
idea  in  this  scheme  was  to  furnish  a  positive  distribution  of 
air  to  all  the  pupils  within  a  room,  and  also  to  take  advan- 
tage of  the  heat  liberated  by  them  in  the  production  of 
upward  moving  currents.  The  new  installation  was  tested 
in  two  ways :  (1)  Simple  tests  were  made  with  anemomet- 
ers placed  at  the  edges  of  the  desks.  Every  test  showed  an 
up  current.  (2)  A  more  striking  test  than  the  one  with  the 
anemometer,  and  one  as  fully  convincing,  or  even  more  so, 
was  a  chemical  test  made  with  ammonia  and  an  indicator 


44  VENTILATING  A  SCHOOL  ROOM 

known  as  phenolphthalein.  This  chemical  test  was  made  as 
follows:  Linen  strings  were  stretched  over  the  rows  of 
desks  at  the  height  of  the  breathing  zone  for  children  seated 
at  the  desks.  Upon  these  strings,  at  intervals  of  ten  or 
twelve  inches,  were  hung  pieces  of  unsized  paper  made  wet 
with  an  alcoholic  solution  of  phenolphthalein.  When  the 
room  was  thus  dotted  over  with  these  wet  papers,  it  looked 
much  like  a  laundry  drying  room  flecked  with  white.  Before 
the  wet  papers  had  time  to  dry,  a  handkerchief,  made  thor- 
oughly  wet  with  concentrated  ammonia  water,  was  hung  in 
the  air  duct  leading  from  the  plenum  chamber,  or  distribut- 
ing room,  to  the  experimental  room.  Within  two  minutes 
after  hanging  the  handkerchief  in  the  duct,  every  paper  on 
the  linen  threads  in  the  experimental  room  became  red  in 
color.  When  ammonia  is  added  to  a  colorless  solution  of 
phenolphthalein,  the  solution  becomes  red;  therefore,  the 
change  in  the  color  of  the  papers  was  conclusive  evidence 
that  ammonia  from  the  handkerchief  had  been  distributed 
to  every  piece  of  paper  wet  with  the  alcoholic  solution.  The 
test  was  repeated  at  another  time  with  the  same  result. 
Still  another  test  was  made  which  contained  an  added  fea- 
ture. In  addition  to  the  papers  supended  in  the  breathing 
zone  over  the  desks  and  seats,  others  were  hung  on  strings 
stretched  parallel  with  those  over  the  rows  of  desks  about 
seven  feet  from  the  floor,  but  directly  over  the  aisles.  In 
this  test  all  the  lower  papers  reddened  in  approximately  the 
same  time  as  before,  and  the  upper  ones  reddened  soon 
thereafter.  These  tests  are  conclusive  evidence  that  the  air 
in  the  experimental  room  is  delivered  to  each  desk,  and  that 
the  movement  of  the  air  in  the  room  is  upward,  and  quite 
uniformly  so.  Moreover,  anemometer  tests  made  at  the 
outlets  of  the  galvanized  iron  tubes  before  the  desks  were 
placed,  showed  that  each  tube  delivers  approximately  the 
same  volume  of  air  in  unit  time. 

THE  EXPERIMENTAL  BOOM  BECOMES  A  HIGH  SCHOOL 

ROOM. 

As  soon  as  the  before-mentioned  changes  in  the  experi- 
mental room  had  been  made  and  tested,  the  room  became  a 
regular  high-school  room,  in  use  throughout  the  day.  It  is 


VENTILATING  A  SCHOOL  ROOM  45 

customary  for  classes  to  change  rooms  for  different  recita- 
tions, and,  therefore,  the  experimental  room  was  occupied 
by  different  classes  each  hour.  This  arrangement  added 
somewhat  to  the  difficulty  of  our  experiments. 

A  REQUIREMENT  FOB  VENTILATION. 

However  satisfactory  the  quantity  of  air  furnished  for 
the  ventilation  of  a  room,  and  however  satisfactory  may  be 
the  means  employed  for  properly  distributing  it,  both  of 
which  in  the  long  run  are  very  important,  nevertheless  the 
human  body  makes  an  immediate  demand  which  may  over- 
shadow either  or  both.  IMMEDIATE  PHYSICAL  COMFORT  is  THE 
STANDARD  OF  THE  HUMAN  BODY,  whatever  the  consequences,  as 
exemplified  either  in  the  drowsy  stupor  that  descends  on 
one  immersed  in  a  hot,  stifling  atmosphere  on  a  cold  wintry 
night,  or  in  the  quiet  repose  that  comes  from  a  balmy  sum- 
mer breeze  outdoors.  Good  ventilation  shall  produce  imme- 
diate comfort. 

One  of  the  most  prominent  as  well  as  immediate  factors 
in  the  production  of  comfort,  is  temperature,  and  therefore 
a  study  was  made  to  determine  the  best  temperature  for  a 
schoolroom.  The  comfort  of  the  human  body  is  largely  in- 
fluenced by  the  temperature  of  the  surrounding  air,  and 
also,  and  at  the  same  time,  by  the  rate  at  which  perspiration 
may  evaporate  into  the  air  from  the  body.  Relative  humid- 
'ity  influences  the  rate  at  which  such  evaporation  occurs,  but 
it  is  only  in  recent  years  that  much  consideration  has  been 
given  to  atmospheric  humidity  in  relation  to  temperature 
and  comfort. 

TEMPERATURE  AND  HUMIDITY  IN  RELATION  TO  COMFORT. 

It  has  become  traditional  in  this  country  that  the  best 
temperature  to  maintain  in  a  room  is  68  to  70  degrees. 
There  are,  however,  some  who  urge  that  these  temperatures 
are  too  high,  and  they  cite  the  English  practice  of  59  to  62 
degrees  as  evidence  of  their  claim.  The  difficulty  with  both 
these  positions  is  that  in  deciding  on  the  best  temperature, 
proper  consideration  is  not  given  to  relative  humidity.  Any 


46  VENTILATING  A  SCHOOL  ROOM 

adult  knows  that  sultry  days  are  much  less  comfortable 
than  days  of  even  higher  temperature  when  the  atmosphere 
is  comparatively  dry.  This  well-known  fact  of  outdoor  ex- 
perience must  be  taken  into  account,  especially  since  it  is 
now  recognized  that  in  cold  weather  we  need  to  humidify 
air  indoors.  On  this  point  of  humidity,  it  may  be  said  that 
the  human  organism  seems  to  be  adapted  to  a  large  range  of 
relative  humidity,  but  it  is  not  accustomed  to  abrupt 
changes  such  as  one  might  experience  on  a  cold  day  in  pass- 
ing from  the  outdoors  into  a  heated  room.  In  a  word,  it 
seems  important  from  the  standpoint  of  health  and  comfort 
to  maintain  a  fair  degree  of  correspondence  between  the 
relative  humidity  of  outdoors  and  indoors. 

Any  system  of  ventilation,  to  be  practicable,  must  pro- 
duce a  feeling  of  comfort,  and  therefore  both  the  tempera- 
ture and  the  relative  humidity  of  the  air  are  important  in 
ventilation.  Temperature  and  relative  humidity  jointly 
help  determine  comfort. 

It  has  generally  been  considered  that  a  temperature  of 
from  68  to  70  degrees  with  a  relative  humidity  of  70  per 
cent,  is  a  most  desirable  condition  to  obtain  (the  70  per  cent 
relative  humidity  also  is  largely  traditional).  In  our  tests 
it  was  assumed  that  the  best  temperature  may  or  may  not 
be  68  to  70  degrees ;  and  also  the  most  satisfactory  relative 
humidity  may  or  may  not  be  70  per  cent. 

The  experimental  room  was  equipped  with  an  auto- 
matic temperature  control,  and  also  an  automatic  humidity 
control.  Moreover,  the  temperature  in  the  different  parts 
of  the  room  was  determined  by  means  of  a  sling  psychro- 
meter.  For  the  most  part,  the  tests  on  relative  humidity 
and  temperature  in  relation  to  comfort,  were  made  by  a 
member  of  the  Commission  and  a  graduate  student  from  the 
University  of  Chicago.  Frequently  individual  high  school 
pupils  in  the  room  were  asked  whether  or  not  they  felt  com- 
fortable, and  in  each  case  the  pupil  answering  did  not  know 
that  any  other  pupil  had  been  asked.  The  teachers  in  charge 
of  the  room  also  were  asked  for  opinions.  All  these  opin- 
ions, together  with  our  own,  served  as  a  basis  for  record. 


48  VENTILATING  A  SCHOOL  ROOM 

COMFORT  ZONE. 
(See  Chart,  page  47.) 

Before  working  very  long,  it  became  evident  that  there 
was  a  temperature  and  humidity  range  within  which  the 
occupants  of  the  rooms  were  comfortable,  and  this  range 
gave  rise  to  what  is  called  the  Comfort  Zone.  This  term, 
comfort  zone,  means  that  there  is  a  maximum  temperature 
with  a  minimum  relative  humidity,  and  minimum  tempera- 
ture with  a  corresponding  maximum  relative  humidity 
between  which  limits  the  occupants  of  a  room  are  comfort- 
able. In  other  words,  there  seems  to  be  no  best  tempera- 
ture and  also  no  best  relative  humidity;  but  the  maximum 
temperature  at  which  one  is  comfortable  will  be  associated 
with  a  minimum  relative  humidity,  and  the  minimum  tem- 
perature for  comfort  will  have  associated  with  it  a  maxi- 
mum relative  humidity.  Under  the  conditions  with  which 
we  were  working,  we  found  that  a  temperature  of  64  to  70 
degrees  with  a  corresponding  relative  humidity  of  55  to  30 
per  cent,  seems  to  be  the  limits;  that  is,  the  comfort  zone 
for  us  was  between  64  degrees  and  55  per  cent  and  70 
degrees  and  30  per  cent. 

It  is  worthy  of  note  that  with  a  temperature  below  67 
or  68,  with  a  proper  relative  humidity,  the  pupils  were  bet- 
ter able  to  give  attention  to  their  work  than  if  the  conditions 
were  otherwise. 

OUTSIDE  WALL  AND  WINDOW  CHILL. 

The  problem  of  how  to  prevent  outside  wall  and  window 
chill  from  seriously  interfering  with  ventilation,  has  never 
been  satisfactorily  solved. 

With  the  change  in  installation  in  the  experimental 
room,  it  was  necessary  to  make  some  provision  for  prevent- 
ing a  sheet  of  cold  air  from  falling  down  the  exposed  walls 
and  windows.  We  tried  to  do  this  by  installing  steam  pipes 
along  the  window  casings  just  in  front  of  the  windows.  The 
idea  in  this  installation  was  to  induce  convection  currents 
around  the  windows,  and  in  this  way  prevent  the  downward 
currents  of  cold  air.  Tests  were  made  of  the  scheme  in  two 
ways:  (1)  By  the  use  of  the  small  turbines  it  was  found 


VENTILATING  A  SCHOOL  ROOM  49 

tliat  down  currents  of  air  were  established  from  a  few  inches 
to  a  foot  or  more  above  the  horizontal  steam  pipes.  A  sec- 
ond method  was  that  of  getting  temperature  readings  at  dif- 
ferent heights  from  the  floor  in  the  aisles  between  the  desks 
and  the  outside  wall.  These  temperature  readings  showed 
a  variation  from  almost  nothing  to  eight  or  ten  degrees, 
between  the  floor  and  the  top  of  the  desks.  During  the  very 
severe  weather  of  January  and  February,  1912,  it  became 
evident  that  this  installation  was  only  partially  satisfac- 
tory. When  the  outside  temperature  was  ten  or  more  de- 
grees below  zero,  there  was  a  cold  current  of  air  that  spilled 
out  from  the  window  over  the  top  of  the  heating  pipes  above 
the  window  sills.  This  fact  led  to  a  proposed  installation 
to  overcome  the  window  chill  in  another  way — by  means  of 
a  sheet  of  hot  air.  This  new  installation  will  be  tried  during 
the  coming  winter. 

VENTILATING  AND  HEATING  COMBINED. 

The  plenum  system  with  which  we  have  worked  com- 
bines the  heating  and  the  ventilating  of  a  building.  The 
heating  is  accomplished  by  means  of  hot  air  which  also  is 
used  subsequently  for  ventilation. 

INSULATED  BUILDINGS. 

Too  much  importance  cannot  be  placed  on  the  quality 
of  construction  in  a  building  in  its  relation  to  the  efficiency 
of  the  ventilating  system.  This  is  particularly  true  with 
reference  to  installation.  In  the  usual  type  of  building 
construction,  it  is  sometimes  necessary,  in  order  to  heat 
the  building  properly,  to  introduce  more  air  than  is 
required  for  ventilation.  The  other  alternative  might  be 
to  introduce  the  air  at  an  unduly  high  temperature,  but 
this  procedure  is  always  objectionable  because  of  its  effect 
upon  the  comfort  of  the  occupants.  When  separate  means 
of  heating  the  building  are  provided,  as  with  direct  radia- 
tion, there  is  a  tendency  to  operate  the  plant  without  venti- 
lation. In  general,  the  lower  it  is  possible  to  maintain  the 
temperature  of  the  incoming  air,  without  discomfort,  the 


50  VENTILATING  A  SCHOOL  ROOM 

better  are  the  results  with  reference  to  ventilation. 
From  the  standpoint  of  economy,  it  is  always  desirable  to 
introduce  no  greater  volume  of  air  than  is  actually  required 
for  ventilating  purposes. 

OUR  LATEST  INSTALLATION. 

Our  first  attempt  at  insuring  an  equitable  distribution 
of  air  for  ventilation  purposes  within  the  experimental 
room  led  us  to  a  more  permanent  installation.  In  the  new 
installation,  we  have  separated  the  heating  of  the  experi- 
mental room  from  the  ventilating,  in  so  far  as  they  seem 
to  impair  the  efficiency  of  each  other.  The  scheme  in  brief 
consists  in  bringing  the  air  for  ventilating  purposes  into  the 
room  through  galvanized  iron  ducts  insulated  with  asbestos 
and  located  under  the  false  floor.  This  system  of  ducts  ter- 
minates in  three-inch  iron  pipes  securely  fastened  to  the 
floor  and  leading  up  under  the  desks.  The  room  is  heated 
by  means  of  hot  air  driven  under  the  floor.  The  idea  in  this 
scheme  is  to  warm  the  floor.  In  order  to  reduce  the  effect 
of  window  chill,  double  windows  are  to  be  installed,  and  the 
heated  air  from  under  the  floor  will  be  forced  upward 
between  the  two  sets  of  windows  and  thus  effectually  over- 
come window  chill.  As  in  the  older  installation,  the  air 
comes  in  below  the  desks  and  leaves  the  room  through 
twelve  registers  in  the  false  ceiling.  The  air  used  for  ven- 
tilating, being  introduced  through  separate  insulated  ducts, 
may  be  at  a  much  lower  temperature  than  that  of  the  air 
used  for  heating. 


Report  of  Test  Made  by  the  Chicago  Commis- 
sion on  Ventilation 

At  the  Office  of 

Joseph  T.  Ryerson  &  Son,  Chicago,  111. 
April  9,  1914 

(See  Plans,  pages  52  and  53.) 

TYPE. 

General  office,  consisting  of  the  entire  top  floor  (3rd) 
of  the  building.  This  is  divided  into  one  very  large  room, 
with  a  few  adjacent  smaller  private  offices.  The  large  room 
has  many  low  partitions,  counters,  etc.  The  ceiling  is  largely 
of  glass  under  a  sawtooth  type  skylight. 

NUMBEK  OP  OCCUPANTS. 
Normally  about  235. 

SYSTEM  OF  HEATING. 

Entirely  indirect  steam  with  both  supply  and  exhaust 
fans,  with  air  washer  and  automatic  temperature  control. 

SYSTEM  OF  VENTILATION. 

By  dilution.  The  inlet  openings  are  about  8  feet  above 
the  floor  on  the  outside  walls,  averaging  about  20  feet  apart. 
The  outlet  openings  are  at  the  floor,  in  the  outside  walls 
and  parallel  with  the  inlet  openings.  Ducts  connect  the  vari- 
ous supply  and  exhaust  flues  with  the  fans,  being  run,  of 
sheet  metal,  along  the  ceiling  of  the  partially  heated  metal 
warehouse  under  the  office. 


54  VENTILATING  AN  OFFICE  BUILDING 

SUPPLY  FANS. 

Two  double  wide  double  inlet  full  housed  8-blade  fans, 
changed,  evidently  after  the  original  installation,  by  adding 
8  blades  about  6  inches  wide  alternating  with  the  original 
blades. 

The  fan  wheels  are  42  inches  in  diameter  and  about  42 
inches  wide  at  the  periphery.  Both  are  on  the  same  shaft 
and  are  operated  at  292  R.  P.  M.  Were  they  of  the  8-blade 
type,  they  should  deliver  22,000  cubic  feet  of  air  per  min- 
ute at  this  speed.  They  are  delivering,  by  anemometer  test 
of  the  tempered  air  which  they  handle,  about  27,000  C.  F.  M. 
This  increase  is  accounted  for  by  the  extra  blades.  The 
fans  are  belt  driven  by  a  15-horsepower  motor. 

EXHAUST  FANS. 

These  have  a  rated  capacity  of  about  80  per  cent  of 
the  capacity  of  the  supply  fans  and  discharge  the  air 
exhausted  from  the  office  into  a  storage  shed. 

INTAKES. 

Cold  air  is  drawn  from  three  windows,  each  4  feet  by 
4  feet  6  inches,  about  30  feet  above  the  street.  The  room 
inlet  openings  have  horizontal  blade  diffusers  installed  by 
the  owner  after  having  had  experience  with  cold  drafts. 

OUTLETS. 

The  outlet  openings  from  the  rooms  are  in  the  side 
walls.  Many  are  obstructed  by  furniture.  There  is  no  pro- 
vision for  any  air  removal  at  or  near  the  ceiling. 

HEATER. 

Eight  rows  of  1-inch  pipe,  controlled  by  diaphragm 
(thennostatic)  valves,  between  the  air  washer  and  the 
intake. 


VENTILATING  AN  OFFICE  BUILDING  55 

Twelve  rows  of  1-inch  pipe,  automatically  controlled, 
between  the  air  washer  and  the  fan. 

Free  area  for  air  passage,  29.2  square  feet. 
Total  surface  2,500  square  feet. 

AIR  WASHEK. 

Multiple  spray  type,  with  automatic  water  line  gover- 
nor and  electric  driven  belted  centrifugal  pump.  The  elim- 
inators are  vertical.  No  humidity  control  or  means  of  heat- 
ing the  water  is  provided.  The  water  was  very  dirty.  The 
eliminator  was  coated  with  dry  deposit,  %  to  %  inch  deep. 
The  washer  is  13  feet  wide,  6  feet  high,  and  5  feet  parallel- 
ing the  direction  of  the  air  passage. 

DUCTS. 

Ducts  are  of  sheet  metal,  have  very  long  runs,  and  are 
figured  for  800  to  1,500  lineal  feet  per  minute  velocity.  They 
are  not  insulated  from  each  other  or  from  the  surrounding 
air,  which  often  gets  as  low  as  30  degrees.  As  the  ducts  are 
rather  minutely  subdivided,  with  separate  automatic  mixing 
dampers  in  each,  the  skin  friction  is  considerable. 

PLENUM  CHAMBER. 

There  are  no  heating  coils  between  the  air  washer  and 
the  fan.  and  the  tempered  air  used  for  cooling  the  office  evi- 
dently is  often  insufficiently  heated.  By  means  of  double 
dampers  and  a  complicated  series  of  baffles  between  the  tem- 
pered air  and  hot  air  chambers,  an  attempt  has  been  made 
to  warm  the  tempered  air  by  forcing  hot  air  to  mix  with  it, 
under  thermostatic  control. 

TIME  OF  TEST. 
2  to  5  P.  M. 


56  VENTILATING  AN  OFFICE  BUILDING 

TEMPERATURES. 

Outside  air,  plus  37  deg.  F. 
At  air  washer,  plus  46  deg.  F. 
Air  washer  water,  plus  46  deg.  F. 
Hot  air  chamber,  plus  98  deg.  F. 
Tempered  air  chamber,  plus  67  deg.  F. 
In  the  office,  average,  plus  72.2,  ranging  from  plus  68  to 
plus  76  deg.  F. 

RELATIVE  HUMIDITY. 

Eelatiye  humidity  outside,  33.5  per  cent. 
Average  in  the  office,  38.4  per  cent,  ranging  from  26  per 
cent  up  to  50  per  cent. 

BACTERIA. 

Petrie  dishes  were  exposed  for  two  minutes  each  at  the 
points  marked  "IX,  2X,"  etc.,  on  the  plans,  with  the  results 
shown  on  the  margin,  following  the  index  numbers. 

AIR  DISTRIBUTION. 

A.  Samples  of  the  air  were  taken  at  the  points  marked 
"A,  B,"  etc.,  on  the  plans,  with  the  results  shown  on  the 
margin,  following  the  index  numbers.    The  outside  C02  at 
the  beginning  of  the  tests  was  3.8  parts  per  10,000. 

B.  Ammonium  chloride  formed  from  the  combination 
of  ammonia  and  hydrochloric  acid  was  introduced  into  the 
plenum  chamber,  to  visualize  the  air  distribution. 

DUST. 

The  dust  content  in  the  entering  air  at  the  supply  win- 
dows was  5,600,000  per  cubic  centimeter.  Between  the  wash- 
er and  the  fans  it  was  4,000,000  per  cubic  centimeter.  In 
the  office,  it  was  1,600,000  as  tested  at  two  representative 
points. 


VENTILATING  AN  OFFICE  BUILDING  57 

DISCUSSION. 

The  plant  has  been  in  use  about  five  years.  The  tem- 
pering coils,  being  exposed  to  the  weather  are  very  rusty. 
Several  pipes,  having  frozen,  are  blanked  off.  The  washer 
is  very  dirty. 

The  fan  wheels  and  housings  are  covered  with  oil  and 
dust  averaging  %  inch  deep.  The  plenum  chamber  and* 
ducts  are  very  rusty.  The  plant  otherwise  is  in  good  order. 
There  is  considerable  discoloration  of  the  walls  around  the 
room  intakes.  The  neighborhood  of  the  plant  is  smoky  and 
dirty. 

-The  average  relative  humidity  was  lower  than  would  be 
desirable,  and  if  an  average  of  45  per  cent  had  been  main- 
tained, greater  comfort  and  a  lower  temperature  would  be 
possible. 

The  bacteria  colonies  were  very  low  in  number,  indi- 
cating excellent  cleaning  in  the  room,  and  an  ability  in  the 
plant  to  maintain  a  high  efficiency  in  this  regard. 

The  carbon  dioxide  analysis  indicates  a  very  poor  fresh 
air  distribution,  as  where  it  showed  by  this  index  12  parts 
of  C02  per  10,000  only  750  cubic  feet  of  air  per  hour  per 
occupant  were  being  delivered  in  such  localities.  For  the 
whole  room  nearly  6,900  cubic  feet  of  air  per  hour  per  occu- 
pant are  really  delivered. 

The  air  distribution  test  showed  that  the  greater  part 
of  the  fresh  air  supply  is  being  delivered  to  the  north  side 
of  the  room.  The  adjustment  of  the  volume  dampers  which 
effected  this  evidently  was  made  in  order  to  warm  the 
room  in  cold  weather,  this  being  especially  necessary  since 
the  heating  plant  is  on  the  south,  and  the  supply  ducts 
are  run  long  distances  in  a  very  cold  place  without  insula- 
tion. 

The  high  dust  content  at  the  inlet  and  the  low  dust 
count  in  the  room  are  striking,  especially  as  the  air  washer 
seems  to  have  an  efficiency  of  but  28  per  cent. 

It  may  be  accounted  for  by  the  disturbance  of  local 
settled-out  dust  in  the  intake  and  fan  rooms  by  the  opera- 
tives of  the  instruments  and  by  the  fact  that  much  of  the 


58  VENTILATING  AN  OFFICE  BUILDING 

dust  so  stirred  up  settled  in  the  fans  and  ducts  before  reach- 
ing the  room. 

CONCLUSIONS. 

The  owner  evidently  made  and  is  making  a  conscien- 
tious endeavor  to  provide  the  best  possible  working  condi- 
tions. The  provision  of  some  direct  radiation  along  the 
north  side,  or  indirect  radiator  boosters  in  the  ducts  running 
to  the  north  side,  by  enabling  the  room  to  be  heated  evenly 
would  permit  of  a  more  perfect  air  distribution,  correcting 
the  condition  indicated  by  the  C02  and  air  distribution  tests. 
The  trouble  would  be  ameliorated  by  heating  the  room  under 
the  office,  or  by  insulating  the  ducts. 

The  supply  fans  are  running  very  slowly  in  considera- 
tion of  the  length  of  the  ducts  and  there  is  ample  power 
to  speed  them  up  to  at  least  350  R.  P.  M.  The  entire  air 
handling  mechanism  should  be  thoroughly  cleaned  at  fre* 
quent  intervals. 

The  installation  of  automatic  humidity  control  is  not 
difficult,  and  would  improve  the  conditions. 

The  closing  of  the  inlet  openings  on  one  side  of  the 
room  and  the  closing  of  all  vent  openings  on  the  opposite 
side  is  suggested  for  use  in  warm  weather  especially,  as  it 
is  believed  that  such  a  procedure  would  insure  a  more  thor- 
ough sweeping  with  fresh  air  of  the  entire  area. 

For  hot  weather  operation,  it  would  probably  be  an 
improvement  if  ceiling  outlets  were  provided,  whereby  the 
hot  air  accumulating  there  by  reason  of  the  sun  effect  could 
be  forced  directly  out  by  the  incoming  cooler  air. 

DEDUCTIONS. 

A  similar  new  plant  should  be  so  designed  that  there 
will  be  no  long  ducts  run  in  cold  air,  especially  to  the  north 
side.  It  should  have  its  vertical  flues  thoroughly  insulated, 
especially  if  they  must  run  up  outside  walls.  It  should 
have  both  floor  and  ceiling  inlets  and  outlets  so  that  efficient 
summer  operation  may  be  effected. 


VENTILATING  AN  OFFICE  BUILDING  59 

INSTRUMENTS. 

The  various  instruments  used  in  this  test  are  described 
in  the  appendix,  pages  70  to  83. 


GV/G4GO 


TEST&FQPr 


/D/9W3 


/70 


Wr±V0a  87//.S&VQD 


Z123 


2:4? 


3,'CO 


3140 


7Z-73 


84-fZ 


77 


go 


€3 


70 


76 


So 


84- 


68 


7B 


So 


80 


80 


79 


80 


8/ 


t-  s/r. 


41 


tz 


7* 


ft 


73 


7* 


go 


s/ 


Cabinet  Tests 

(See  Plate  3,  page  86.) 

A  series  of  cabinet  tests  is  being  conducted  by  the  Com- 
mission under  varying  air  conditions,  with  particular  ref- 
erence to  volume,  movement,  temperature,  humidity,  carbon 
dioxide,  dust  and  bacteria.  It  is  the  intention  to  repeat 
these  tests  with  subjects  of  different  types. 

The  cabinet,  which  is  shown  in  the  accompanying  illus- 
tration, is  built  of  heavy  galvanized  iron,  28  inches  wide,  6 
feet  long,  and  6  feet  high.  All  seams  are  soldered  and 
painted.  On  one  side  are  two  observation  windows,  each 
2  feet  square.  At  one  end  is  an  air  tight  door,  and  at  the 
other  end  is  a  three-speed  direct  connected  Sirocco  fan, 
having  a  maximum  capacity  of  84  C.  F.  M.  The  installation 
of  the  fan  is  such  that  the  air  may  be  re-circulated  in  the 
cabinet,  or  fresh  air  introduced.  The  fan  discharges  the  air 
into  the  cabinet  through  either  or  both  of  two  compartments 
in  which  chemicals  or  other  material  may  be  placed  for  con- 
trolling the  temperature,  humidity,  C02,  etc.  In  addition 
to  the  above  a  small  air  washer  is  about  to  be  installed. 

The  cabinet  easily  accommodates  two  persons.  The 
tests  are  usually  conducted  with  two  subjects  of  different 
age  and  type,  at  the  same  time,  in  order  to  obtain  a  check 
on  the  effects  noted. 

Observations  are  taken,  at  stated  periods  throughout 
the  tests,  of  the  air  conditions  as  well  as  the  physical  and 
mental  condition  of  the  subjects. 

The  tests  thus  far  have  been  only  of  a  preliminary 
nature,  to  enable  us  to  determine  the  best  method  of  con- 
ducting them,  and  also  to  determine  the  best  apparatus 
required  to  maintain  the  desired  atmospheric  conditions. 

Five  of  these  tests  have  been  made,  ranging  from  one 
to  three  hour  periods  and  an  illustration  of  one  of  the  test 
sheets  is  given  herein. 


Revised  List   of  Resolutions   of  the  Chicago 
Committee  on  Ventilation 

November,  1913 

1.  RESOLVED,  That  carbon  dioxide,  as  encountered  in 
working  practice  is  not  the  harmful  agent  of  major  impor- 
tance in  expired  air  or  air  otherwise  contaminated. 

2.  RESOLVED,  That  a  temperature  of  68  deg.  F.  with  a 
proper  relative  humidity  is  the  proper  maximum  tempera- 
ture for  living  rooms  artificially  heated. 

3.  RESOLVED,  That  in  the  present  state  of  knowledge, 
it  is  impossible  to  designate  all  harmful  factors  in  or  asso- 
ciated with  expired  air. 

4.  RESOLVED,  That  the  principle  of  ventilation  by  cur- 
rents is  preferable  to  the  principle  of  ventilation  by  dilution. 

5.  RESOLVED,  That  for  adequate  ventilation,  smaller 
volumes  of  air  suffice  when  introduced  by  currents  than 
when  introduced  by  dilution. 

6.  RESOLVED,  That  ventilation  which  utilizes  the  prin- 
ciple of  convection  in  producing  currents  is  more  effective 
and  economical  than  that  which  neglects  this  principle. 

7.  RESOLVED,  That    upward   ventilating    currents    in 
crowded  rooms  are  desirable,  provided  the  sources  of  air 
supply  are  free  from  contamination. 

8.  RESOLVED,  That  in  making  use  of  upward  ventila- 
tion, attention  should  be  given  to  the  counteracting  of  wall 
and  window  chill. 

9.  RESOLVED,  That  in  those  processes  of  manufacture 
where  considerable  CO2  is  liberated,  the  C02  content  is  not 
a  proper  index  of  air  pollution. 

10.  RESOLVED,  That  for  the  removal  of  kitchen  odors, 
body  odors,  stable  odors,  and  other  odors  associated  with 
heat  production,  upward  ventilation  is  more  efficient  than 
downward  ventilation. 


REVISED  LIST  OF  RESOLUTIONS  63 

11.  RESOLVED,  That  the  delivery  of  a  certain  volume  of 
air  per  unit  of  time,  per  occupant,  into  a  given  space  does 
not  necessarily  constitute  ventilation. 

12.  RESOLVED,  That  air  which  is  introduced  into  an 
occupied  room  in  such  a  way  that  it  strikes  the  occupants 
should  be  not  lower  in  temperature  than  60  deg.  F. 

13.  RESOLVED,  That  heating  and  ventilating  are  two 
distinct  problems,  and  therefore,  the  installation  of  heating 
and  ventilating  systems,  whether  separate  or  combined, 
should  be  such  that  neither  system  shall  interfere  with  the 
efficiency  of  the  other. 

14.  RESOLVED,  That  from  the  standpoint  of  health,  rel- 
ative humidity  is  one  of  the  important  factors  in  ventilation. 

15.  RESOLVED,  That  efficient  air  cleaning  devices  are 
desirable  in  all  ventilating  installations  where  the  air  sup- 
ply is  liable  to  be  contaminated  by  dust,  or  other  objection- 
able matter. 

16.  RESOLVED,  That  the  bacterial  content  of  the  air  is 
an  important  factor  in  all  ventilation,  arid  bears  a  direct 
relation  to  the  source  and  quantity  of  air  supply. 

CAR  VENTILATION. 
STREET  CARS. 

17.  RESOLVED,  That  ventilation  by  deck  sash  is  never 
satisfactory  in  street  cars. 

18.  RESOLVED,  That  either  the  plenum  or  the  vacuum 
principle  of  ventilation  is  applicable  to  the  ventilation  of 
street  cars. 

19.  RESOLVED,  That  air  inlets  should  be  of  such  size 
and  location  that  drafts  are  not  perceptible  when  the  air 
enters  at  a  temperature  of  from  50  to  60  deg.  F. ;  and  they 
should  be  of  such  number  and  distribution  as  to  supply  the 
maximum  number  of  occupants  with  the  proper  amount  of 
air. 

20.  RESOLVED,  That  in  street  car  ventilation,  the  use 
of  a  plenum  system  without  outlets,  or  an  exhaust  system 
without  inlets  is  not  compatible  with  a  high  degree  of  effi- 
ciency. 


64  REVISED  LIST  OF  RESOLUTIONS 

21.  RESOLVED,  That    air    delivered    into    street    cars 
should  be  not  colder  than  50  deg.  F. 

22.  RESOLVED,  That  in  street  cars  in  which  wraps  are 
worn,  a  temperature  of  not  less  than  50  deg.  F.  or  more 
than  60  deg.  F.   should  be  maintained  during   artificial 
heating. 

ELEVATED  CARS. 

23.  RESOLVED,  That  ventilation  by  the  deck  sash  is 
never  satisfactory  in  elevated  cars. 

24.  RESOLVED,  That  either  the  plenum  or  vacuum  prin- 
ciple of  ventilation  is  applicable  to  the  ventilation  of  cars 
on  elevated  railways. 

25.  RESOLVED,  That  inlets  should  be  of  such  size  and 
location  that  drafts  are  not  perceptible  when  the  air  enters 
at  a  temperature  of  from  50  to  60  deg.  F. ;  and  they  should 
be  of  such  number  and  distribution  as  to  supply  the  maxi- 
mum number  of  occupants  with  the  proper  amount  of  air. 

26.  RESOLVED,  That  in  elevated  car  ventilation,  the  use 
of  a  plenum  system  without  outlets  or  of  an  exhaust  system 
without  inlets  is  not  compatible  with  a  high  degree  of  effi- 
ciency. 

27.  RESOLVED,  That  air  delivered  into  elevated  cars 
should  not  be  colder  than  50  deg.  F. 

28.  RESOLVED,  That  in  elevated  cars,  in  which  wraps 
are  worn,  a  temperature  of  not  less  than  50  deg.  F.  or  more 
than  60  deg.   F.   should  be  maintained  during   artificial 
heating. 

RAILROAD  CARS. — Day  Coaches,  Sleeping  Cars,  Suburban 
Cars,  and  other  Cars  making  long  runs. 

29.  RESOLVED,  That  ventilation  by  the  deck  sash  alone 
is  never  satisfactory  in  railroad  cars. 

30.  RESOLVED,  That  either  the  plenum  or  vacuum  prin- 
ciple of  ventilation  is  applicable  to  the  ventilation  of  rail- 
road cars. 

31.  RESOLVED,  That  inlets  should  be  of  such  size  and 
location  that  drafts  are  not  perceptible  when  the  air  enters 
at  a  temperature  of  from  50  deg.  to  60  deg.  F. ;  and  they 
should  be  of  such  number  and  distribution  as  to  supply  the 
maximum  number  of  occupants  with  the  proper  amount  of 
air. 


REVISED  LIST  OF  RESOLUTIONS  65 

32.  RESOLVED,  That  in  the  ventilation  of  railroad  cars, 
except  sleeping  cars,  the  use  of  a  plenum  system  without 
outlets  or  of  an  exhaust  system  without  inlets  is  not  com- 
patible with  a  high  degree  of  efficiency. 

33.  RESOLVED,  That  air  delivered  into  railroad  cars 
should  not  be  colder  than  50  deg.  F. 

STANDARDS. 

34.  RESOLVED,  That  the  following   standards   should 
apply  to  the  ventilation  of  cars : 

Street  cars,  elevated  cars,  or  other  cars  making  fre- 
quent stops,  during  which  the  doors  are  opened,  shall  be 
so  ventilated  that  the  amount  of  air  entering  the  car  for 
ventilation,  through  openings  provided  for  such  purposes, 
shall  be  at  the  rate  of  not  less  than  500  cubic  feet  per  hour, 
per  occupant,  based  upon  the  maximum  carrying  capacity 
(seats  and  standing  room  included)  of  such  car,  provided 
that  the  total  amount  from  all  sources  shall  not  be  less  than 
750  cubic  feet  per  hour. 

Day  coaches,  sleeping  cars,  suburban  cars,  and  other 
cars  making  long  runs,  shall  be  so  ventilated  that  the 
amount  of  air  entering  the  car  for  ventilation,  through  open- 
ings provided  for  such  purpose,  shall  be  at  the  rate  of  not 
less  than  one  thousand  (1,000)  cubic  feet  per  hour,  per  occu- 
pant, based  upon  the  maximum  seating  capacity  of  such  car. 

Smoking  cars  and  smoking  compartments  in  cars  shall 
be  so  ventilated  that  the  amount  of  air  introduced  for  ven- 
tilation shall  be  at  least  20  per  cent  in  excess  of  the  amount 
required  for  the  same  type  of  car  under  the  above  standard. 

35.  RESOLVED,  That  the  carbon  dioxide  content  of  the 
air  of  cars  should  not  exceed  ten  parts  by  volume  in  each 
ten  thousand  (10,000)  parts  of  air;  provided  that  in  street 
cars,  elevated  cars,  and  other  cars  used  in  local  interurban 
service  the  carbon  dioxide  content  may  not  rise  above 
twelve  parts  by  volume  in  each  ten  thousand  (10,000)  parts 
of  air. 


66  REVISED  LIST  OF  RESOLUTIONS 

PICTURE  THEATERS. 

36.  RESOLVED,  That  in  the  ventilation  of  picture  thea- 
ters provision  must  be  made  for  warming  and  regulating 
the  temperature  of  the  air  introduced. 

37.  RESOLVED,  That  when  cold  air  for  ventilation  is 
introduced  into  picture  theaters  above  the  breathing  zone, 
either 

(1)  There  will  be  an  insufficient  supply  of  air  for  prop- 
er ventilation,  or 

(2)  The  occupants  of  the  theater  will  be  uncomfortably 
cold. 

38.  RESOLVED,  That    upward    ventilation    in    picture 
theaters  is  more  efficient  than  downward  ventilation;  also 
it  is  more  economical  from  the  standpoint  of  operation. 

39.  RESOLVED,  That  in  the  ventilation  of  picture  thea- 
ters the  fans  and  ducts  should  be  designed  for  a  pressure 
not  exceeding,  in  normal  cases,  %  ounce  per  square  inch. 

40.  RESOLVED,  That  in  the  ventilation  of  picture  thea- 
ters in  which  furnace  heating  apparatus  is  used,  the  space 
between  the  furnace  and  its  casing  must  be  under  air  pres- 
sure at  all  times  when  the  fan  is  in  operation. 

41.  RESOLVED,  That  when  furnace  heating  apparatus 
is  used  in  the  ventilation  of  picture  theaters,  the  furnace 
must  never  be  under  suction  when  the  fan  is  in  operation. 

42.  RESOLVED,  That  in  the  downward  ventilation  of 
picture  theaters,  the  room  must  be  practically  an  air-tight 
enclosure  above  the  breathing  zone. 

43.  RESOLVED,  That  in  the  cooling  of  picture  theaters 
in  the  summer  time,  the  system  of  downward  ventilation  is 
inefficient. 

44.  RESOLVED,  That  air  delivered  into  picture  theaters 
for  ventilation  purposes  should  not  be  delivered  at  a  tem- 
perature colder  than  60  deg.  F. 

45.  RESOLVED,  That  the  temperature  in  picture  thea- 
ters at  the  breathing  zone  should  not  be  lower  than  60  deg. 
F.  nor  higher  than  70  deg.  F. 

46.  RESOLVED,  That  in  the  breathing  zone  the  number 
of  colonies  of  bacteria  on  a  standard  agar  plate  should  never 
exceed  15  for  a  five-minute  exposure. 


REVISED  LIST  OF  RESOLUTIONS  67 

47.  RESOLVED,  That  the  carbon  dioxide  content  of  the 
air  in  the  breathing  zone  in  picture  theaters  should  not 
exceed  10  parts  per  ten  thousand. 

48.  RESOLVED,  That  the  relative  humidity  of  the  air 
when  brought  into  picture  theaters  for  ventilation  pur- 
poses should  not  be  less  than  35  per  cent. 

49.  RESOLVED,  That  the  velocity  of  the  air  delivered 
into  picture  theaters  for  ventilation  purposes  by  upward 
ventilation  shall  not  exceed  150  feet  per  minute. 

50.  RESOLVED,  That  the  quantity  of  air  delivered  into 
picture  theaters  for  ventilation  purposes  shall  not  be  less 
than  25  cubic  feet  per  occupant  per  minute.     It  shall  be 
understood  that  in  determining  such  quantity,  the  maximum 
seating  capacity  shall  be  considered  as  the  number  of  occu- 
pants of  the  room. 

51.  RESOLVED,  That  fresh  air  registers  in  the  floors  of 
the  aisles  and  lobbies  of  picture  theaters  should  be  pro- 
hibited. 

52.  RESOLVED,  That  both  the  design  and  location  of 
fresh  air  inlets  in  picture  theaters  should  be  such  as  to 
minimize  the  possibility  of  contaminating  them  or  the  air 
which  they  deliver. 

SCHOOL  ROOMS. 

53.  RESOLVED,  That  either  the  plenum  or  vacuum  prin- 
ciple is  applicable  to  the  ventilation  of  school  rooms. 

54.  RESOLVED,  That  in  the  artificial  ventilation  of  a 
school  room,  the  air  inlets  and  outlets  should  be  of  such 
size,  number,  and  location  as  to  insure  equal  distribution 
of  air  throughout  the  room. 

55.  RESOLVED,  That  the  maximum  temperature  for  a 
school  room,  artificially  heated,  should  not  be  more  than  68 
deg.  F. 

56.  RESOLVED,  That  the  relative  humidity  of  a  school 
room,  artificially  heated,  should  not  fall  below  40  per  cent. 

57.  RESOLVED,  That  in  the  present  state  of  knowledge 
and  practice  the  quantity  of  air  supplied  to  school  rooms 
for  ventilation  should  not  be  less  than  30  cubic  feet  per  pupil 
per  minute. 


68  REVISED  LIST  OF  RESOLUTIONS 

58.  RESOLVED,  That  both  the  design  and  location  of  the 
air  intake  for  a  school  building  should  be  such  as  to  minim- 
ize the  possibility  of  contaminating  the  air  supply. 

59.  RESOLVED,  That  efficient  air  cleaning  devices  are 
desirable  in  all  ventilating  installations  where  the  air  sup- 
ply is  liable  to  be  contaminated  by  dust,  or  other  objection- 
able matter. 

60.  RESOLVED,  That  in  the  automatic  control  of  tem- 
perature within  a  school  room,  the  thermostat  should  be  so 
located  as  not  to  be  influenced  by  wall  chill.    The  thermostat 
should  be  so  located  as  to  be  influenced  by  the  average  tem- 
perature of  the  room  only. 

61.  RESOLVED,  That  in  mechanically  ventilated  school 
buildings,  it  is  desirable  at  stated  periods  to  flush  all  the 
school  rooms  in  the  building  with  fresh  air  by  means  of  open 
windows. 

62.  RESOLVED,  That  careful  consideration  should  be 
given  to  the  sweeping  and  cleaning  of  the  school  room  as 
effecting  its  ventilation. 

63.  RESOLVED,  That  the  temperature  of  a  school  room 
should  be  kept  as  low  as  the  comfort  of  its  occupants  will 
permit;  and  that  the  temperature  may  be  kept  down  by 
increasing  the  relative  humidity. 

64.  RESOLVED,  That  in  the  proper  ventilation  of  a 
school  building  in  cold  weather,  it  is  necessary  to  provide 
means  for  humidifying  the  air  introduced  into  the  building. 
(See  note.) 

65.  RESOLVED,  That  a  constant  temperature  and  a  con- 
stant relative  humidity  are  not  conducive  to  the  highest 
degree  of  comfort  in  a  school  room. 

66.  RESOLVED,  That  in  the  production  of  comfort  for 
the  occupants  of  a  school  room,  the  maximum  temperature 
should  be  associated  with  a  minimum  relative  humidity,  and 
the  minimum  temperature  should  be  associated  with  a  maxi- 
mum relative  humidity. 

67.  RESOLVED,  That  in  a  school  building  artificially 
ventilated  and  heated  the  comfort  zone  should  be  estab- 
lished in  order  that  the  engineer  may  properly  operate  the 
heating  and  ventilating  system. 


REVISED  LIST  OF  RESOLUTIONS  69 

68.  RESOLVED,  That  the  carbon  dioxide  content  alone 
is  not  always  an  index  of  the  contamination  of  air  for  venti- 
lating purposes,  within  an  enclosure. 

NOTE  :  Relative  humidity  may  be  increased  in  a  school 
room  by  means  of  properly  muffled  jets  of  steam  introduced 
into  the  plenum  or  fan  chambers  from  the  boiler  supply. 


Methods  and  Devices  Employed 

This    appendix   describes    the   methods    and    devices 
employed  by  the  Commission  in  making  tests. 
A — AIR  VELOCITIES  : 

1.  Anemometer. 

2.  Pitot  Tube  and  Gauge. 
AIE  MOVEMENTS  : 

1.  Ammonium  Chloride  Test. 

2.  Phenolphthalein  Tests. 

3.  Balloon  Tests. 

4.  Pin  Wheel  Tests. 
AIR  ANALYSES  (C02) : 

1.  Method  of  Taking  Samples. 

2.  Petterson-Palmquist  Apparatus. 
B — BACTERIA  : 

1.  Cultures. 

2.  Caldwell  Tubes. 

3.  Sand  Filters. 

C — CABINET  TEST  METHODS  : 

1.  Sphygmomanometer. 

2.  Thermometers. 

3.  Psychrometers. 

4.  Air  Samples. 

5.  Cultures. 
D— DUST: 

1.  Sugar  Filter. 

2.  Koniscope. 

3.  Aiken  Portable  Dust  Counter. 
E — STANDARD  CANDLES. 

A — AIR  VELOCITIES. 

The  velocity  of  air  or  other  gases  may  be  measured 
directly  by  means  of  an  anemometer,  or  indirectly  by  com- 


METHODS  AND  DEVICES  EMPLOYED  71 

puting  the  velocity  from  the  differences  in  pressure  that 
cause  the  flow,  measured  with  the  Pitot  tube  and  gauge. 

ANEMOMETER. 
(See  Plate  4,  page  87.) 

The  Biram  pattern  anemometer  consists  of  a  small 
wheel  carrying  8  vanes.  The  wheel  is  connected  by  suitable 
gearing  to  indicating  hands  on  the  dial  and  the  instrument 
so  calibrated  that  the  revolutions  of  the  vanes  indicate  the 
velocity  of  air  in  feet  per  unit  of  time.  The  wide  diver- 
gence in  the  readings  obtained  by  two  persons  with  the  same 
anemometer,  under  the  same  conditions,  should  not  be  at- 
tributed to  inaccuracy  of  the  instrument,  but  rather  to 
ignorance  or  carelessness  in  its  use. 

The  first  requisite  is  that  the  instrument  be  in  good 
repair  and  properly  calibrated.  The  second  is  that  the 
readings  be  accurately  timed.  The  third  is  that  the  proper 
method  of  taking  the  readings  be  employed. 

In  taking  readings  at  the  register  face  the  method  of 
slowly  moving  the  anemometer  across  the  register  or  up 
and  down  as  the  case  may  be,  is  only  mentioned  to  be  con- 
demned. The  reading  will  be  inaccurate  except  at  those 
registers  where  the  velocity  is  uniform  throughout  the 
entire  area.  In  taking  readings,  where  the  velocity  varies 
over  different  areas  of  the  register  face,  it  can  readily  be 
seen  that  in  moving  the  instrument  slowly  across  the  face 
of  the  register  the  momentum  acquired  by  the  revolving 
vane  over  the  areas  of  high  velocity  will  cause  it  to  continue 
to  revolve  at  a  much  higher  rate  than  it  should  while  pass- 
ing over  the  areas  of  low  velocity,  consequently  a  higher 
average  velocity  reading  will  be  obtained  than  the  condi- 
tions warrant.  The  proper  method  is  to  divide  the  face  of 
the  register  or  other  opening  into  equal  areas  of  approxi- 
mately 6  inches,  and  take  one-half  or  one  minute  readings 
at  the  center  of  each  square.  The  average  of  the  total  num- 
ber of  readings  times  the  area  of  the  opening  will  give  the 
cubic  feet  of  air  delivered. 


72  METHODS  AND  DEVICES  EMPLOYED 

PITOT  TUBE. 
(See  Plate  5,  page  87.) 

The  velocity  of  air  flowing  through  a  given  duct  de- 
pends on  the  difference  in  pressure  maintained  between  the 
entrance  and  outlet.  It  is  necessary  to  consider  this  pres- 
sure as  made  up  of  two  components:  (1)  that  which  is 
required  to  compensate  or  overcome  the  loss  due  to  com- 
pression and  frictional  resistance  (static  pressure) ;  (2) 
that  which  is  necessary  to  move  the  volume  of  air  at  the 
given  velocity  (velocity  pressure).  The  sum  of  the  two  is 
the  total  or  dynamic  pressure.  The  air  velocity  is  deter- 
mined from  the  formula  v  =  V2  gh,  which  transferred  into 
terms  of  air  becomes  v  =  1096.5  V~|r  where  v  is  the  velocity 
in  feet' per  minute,  P  is  the  velocity  pressure  in  inches  of 
water,  and  W  is  the  weight  of  one  cubic  foot  of  air  at  the 
given  temperature. 

As  there  is  no  way  of  determining  the  velocity  pres- 
sure directly  the  total  and  static  pressures  must  be  deter- 
mined and  the  latter  subtracted  from  the  former  to  obtain 
the  velocity  pressure.  For  making  these  determinations  the 
Pitot  Tube  is  the  most  satisfactory  instrument  from  the 
standpoint  of  accuracy  and  convenience.  The  tube  used 
by  the  Commission  is  of  the  American  Blower  type,  48 
inches  long  with  a  tip  4%  inches  long.  The  static  openings 
are  four  in  number,  two  on  either  side,  and  .02  of  an  inch 
in  diameter.  The  static  branch  of  the  tube  is  on  the  for- 
ward or  tip  side  and  the  total  pressure  branch  at  the  rear. 

The  readings  are  taken  on  an  Ellison  draft  gauge,  the 
scale  graduated  to  .01  of  an  inch.  The  gauge  has  been  pro- 
vided with  a  special  head  and  leveling  device  to  be  used  in 
connection  with  a  level  tripod.  This  makes  a  combination 
that  is  portable,  can  be  set  up  in  any  location  and  leveled 
quickly  and  accurately.  (See  Plate  6,  page  88.) 

AIR  MOVEMENTS. 

The  velocity  and  direction  of  air  movements  in  audi- 
toriums, school  rooms,  etc.,  are  studied  by  means  of  the 


METHODS  AND  DEVICES  EMPLOYED  73 

ammonium  chloride  test,  phenolphthalein  indicators,  small 
counterpoised  balloons,  and  pin  wheels. 
(1)     AMMONIUM  CHLORIDE  TEST: 

When  strong  NH4OH  and  HC1  are  volatilized  and  the 
two  gases  brought  into  contact,  a  chemical  reaction  results 
with  the  production  of  NH4C1.  This  ammonium  chloride 
occurs  in  a  very  finely  subdivided  state,  is  distinctly  visible 
as  a  white  cloud,  and  does  not  readily  settle  out  of  the  air. 
This  is  a  valuable  method  of  studying  air  currents  visually. 

The  test  is  made  by  saturating  large  desk  blotters  with 
the  two  reagents,  bringing  them  in  close  proximity,  6  or  8 
inches  from  each  other,  and  shaking  the  blotters  gently. 
The  ammonium  chloride  is  liberated  as  a  cloud  in  the  man- 
ner described,  usually  at  a  fresh  air  intake.  The  course 
which  it  takes  and  the  velocity  of  its  travel  are  noted.  With 
100  cc  of  each  of  these  reagents  enough  ammonium  chloride 
can  be  produced  to  become  visible  throughout  the  auditor- 
ium of  a  moving  picture  theater  in  about  five  minutes.  The 
following  modification  of  this  test  is  useful  where  local  air 
currents  are  to  be  studied : 

The  ammonium  hydroxide  is  placed  in  one  of  the  small 
125  cc  bottles  and  the  acid  in  another.  By  means  of  the  air 
sampling  bulb,  air  is  driven  through  these  two  bottles  sim- 
ultaneously, and  the  finely  divided  ammonium  chloride  is 
formed  at  the  nozzle  of  the  apparatus.  (See  Plate  7,  page 
88.)  With  this  apparatus,  a  dense  white  cloud  of  ammonium 
chloride  may  be  produced  in  any  locality  desired  and  its 
course  and  velocity  studied. 
(2)  PHENOLPHTHALEIN  TEST:  (See  Plate  8,  page  89.) 

This  test  depends  upon  the  reaction  which  occurs  in  a 
weak  alcoholic  solution  of  phenolphthalein  when  acted  upon 
by  a  strong  alkaline  reagent.  For  this  test  Soxhlet  extrac- 
tion shells  are  suspended  by  strings  from  wires  at  various 
points  throughout  the  room  where  test  is  being  conducted. 
A  pledget  of  absorbent  cotton  saturated  with  distilled  water 
is  placed  in  the  shell.  The  outside  is  saturated  with  a  y2 
per  cent  solution  of  phenolphthalein  in  60  per  cent  alcohol. 
Strong  ammonium  hydroxide  is  then  volatilized  at  the  fresh 
air  intake  and  the  time  when  the  reaction  at  various  sta- 


74  METHODS  AND  DEVICES  EMPLOYED 

tions  is  observed,  noted.  This  gives  us  a  method  of  deter- 
mining the  time  required  for  the  air  supply  to  reach  the 
various  locations  where  the  indicators  are  placed. 

(3)  BALLOON  TEST: 

Small  toy  balloons  are  inflated  with  hydrogen  gas  and 
counterpoised  with  small  improvised  weights.  These 
weights  are  just  sufficient  to  keep  the  balloons  in  the  air  at 
the  temperature  in  which  the  test  is  being  made.  They  are 
liberated  at  various  points  and  give  a  very  interesting  vis- 
ual demonstration  of  air  travel  and  the  action  of  air  cur- 
rents. As  the  balloons  become  less  buoyant  some  of  the 
counterpoising  weight  is  removed. 

(4)  PIN  WHEEL  TEST  : 

During  the  experimental  work  at  the  Chicago  Normal 
College,  Professor  Shepherd  devised  these  pin  wheels  for 
testing  vertical  air  currents,  especially  the  effect  produced 
on  the  movements  of  air  in  a  room  by  wall  and  window 
chill.  The  pin  wheel  is  constructed  of  very  light  aluminum 
foil  fastened  into  a  cork  hub,  and  balanced  on  a  fine  cambric 
needle  thrust  into  cork  or  other  suitable  substance  to  form 
a  base.  A  thin  glass  pivot  made  by  drawing  glass  tubing 
may  be  used  instead  of  the  needle.  These  little  devices 
are  so  delicate  that  the  air  currents  produced  from  the  heat 
of  the  experimenter's  hand  will  cause  the  wheel  to  revolve. 

AIR  ANALYSES. 

(1)     SAMPLING  DEVICE  :     (See  Plate  9,  page  89.) 

After  experimenting  with  various  methods  of  taking 
air  samples  for  C02  analysis  the  following  has  been 
adopted : 

The  apparatus  consists  of  a  clean  rubber  stoppered 
bottle  of  about  120  cc  capacity,  a  Paquelin  cautery  bulb  and 
24  inches  of  tubing.  The  apparatus  is  held  at  arm's  length 
from  the  body,  great  care  being  exercised  that  the  expired 
air  from  the  observer's  mouth  does  not  contaminate  the 
samples.  The  cork  is  removed  and  the  tube  inserted  to  the 
bottom  of  the  bottle.  The  tube  is  closed  by  pressing  it 
between  the  thumb  and  the  neck  of  the  bottle  and  the  bulb 
is  compressed  until  the  reservoir  is  distended.  The  thumb 
pressure  is  then  released  and  the  air  in  the  reservoir  allowed 


METHODS  AND  DEVICES  EMPLOYED  75 

to  rush  into  the  bottle,  displacing  the  residual  air.  This 
operation  is  repeated  three  times  in  order  to  be  sure  that 
all  of  the  air  originally  in  the  bottle  and  apparatus  has 
been  replaced  by  the  air  to  be  sampled.  The  tube  is  then 
removed,  the  bottle  corked  and  sealed  and  taken  to  the 
laboratory  for  analyses. 
(2)  ANALYSES  OF  AIR  SAMPLES  :  (See  Plate  10,  page  90.) 

Analyses  are  made  for  carbon  dioxide  with  the  modi- 
fied Petterson-Palmquist  apparatus.  This  consists  essen- 
tially of  a  manometer  (A)  for  obtaining  similar  pressure 
conditions  at  the  beginning  and  end  of  the  analyses;  an 
absorption  chamber  (B)  for  removing  the  carbon  dioxide 
in  the  sample,  by  means  of  potassium  hydroxide;  and  a 
graduated  scale  (E)  for  reading  the  volume  of  the  sam- 
ple before  and  after  the  carbon  dioxide  has  been  removed. 

The  absorption  chamber  with  its  potassium  hydroxide 
chamber,  the  bulb  of  the  pipette,  and  the  pressure  compen- 
sating chamber,  are  all  enclosed  in  a  glass  case  and  sub- 
merged in  water  to  prevent  slight  changes  in  the  tempera- 
ture of  the  room  from  effecting  the  air  under  analysis.  By 
means  of  an  air  bulb  and  a  short  piece  of  glass  tubing,  the 
water  in  this  chamber  is  continually  kept  in  motion  during 
the  analysis. 

The  procedure  is  as  follows:  (See  Plates  11  and  12, 
pages  91  and  92.) 

In  analyzing  a  sample  the  mercury  cup  "  F  "  is  raised 
until  the  mercury  fills  the  bulb  of  the  pipette  "D,"  the 
bottle  containing  the  sample  of  air  is  now  connected  to 
"0"  by  a  piece  of  rubber  tubing,  "N"  being  open;  the 
mercury  cup  is  lowered  until  the  mercury  rests  at  zero. 
This  draws  the  sample  of  air  into  the  bulb  of  the  pipette, 
which  holds  25  cc.  Salt  water  is  allowed  to  flow  into  the 
air  sample  bottle  to  replace  the  air  which  is  drawn  into 
the  apparatus.  The  stop  cock  "N"  is  now  closed,  "P" 
opened  and  the  location  of  the  bubble  in  the  manometer 
recorded.  "  P  "  is  now  closed  and  "  M  "  opened.  By  lifting 
the  mercury  cup  the  air  is  now  driven  over  into  the  absorp- 
tion chamber  "B,"  the  bulb  again  lowered  and  the  air  is 
returned  to  the  pipette.  This  is  repeated  three  times  when 
all  of  the  carbon  dioxide  in  the  sample  will  have  been 


76  METHODS  AND  DEVICES  EMPLOYED 

absorbed.  The  air  is  now  brought  back  into  the  pipette 
and  the  mercury  column  lowered  until  the  potassium 
hydroxide  stands  at  exactly  the  same  level  it  did  at  the 
beginning  of  the  analysis.  The  stop  cock  '  *  M  "  is  now  closed 
and  "P"  opened  and  by  means  of  the  pressure  thumb  screw 
"G-,"  the  pressure  is  increased  or  reduced  until  the  mano- 
meter bubble  registers  the  same  pressure  that  it  did  before 
the  carbon  dioxide  was  removed  from  the  sample.  This  com- 
pletes the  analysis,  the  reduction  in  volume  being  read 
directly  on  the  graduated  scale  in  parts  of  C02  per  10,000 
parts  of  air. 

B — BACTEEIA. 

(1)     CULTURES:     (See  Plate  13,  page  93.) 

Agar  plates  are  made  by  pouring  10  cc  of  agar,  made 
according  to  the  formula  set  as  standard  by  the  American 
Public  Health  Association  for  water  and  milk  analyses,  into 
Petrie  dishes  10  centimeters  in  diameter.  These  plates  are 
exposed  5  or  10  minutes  in  theaters  and  2  minutes  in  street 
cars.  They  are  incubated  for  48  hours  at  room  temperature 
and  the  colonies  which  develop,  counted.  A  quantitative 
count  has  been  made  in  some  instances  by  means  of  a  tube 
recently  devised  by  Dr.  Caldwell  of  the  Municipal  Labora- 
tories. This  is  a  galvanized  iron  tube  13  inches  long  and 
about  3V2  inches  in  diameter,  capped  at  both  ends.  The  tube 
is  of  such  dimensions  that  its  capacity  is  exactly  2  liters.  In 
taking  a  sample  of  air  the  caps  from  both  ends  are  removed, 
the  tube  passed  through  the  air  by  a  horizontal  motion  until 
the  observer  is  confident  that  all  the  air  in  the  tube  has  been 
replaced  by  the  air  in  the  room.  The  upper  cap,  is  now 
replaced  and  the  tube  inverted  over  an  uncovered  Petrie 
dish  and  allowed  to  stand  for  20  minutes.  At  the  end  of 
this  time,  it  has  been  determined  experimentally  that  all 
of  the  bacteria  in  the  tube  will  have  settled  on  the  plate, 
which  is  then  incubated  and  the  colonies  counted.  Enough 
work  has  not  as  yet  been  done  with  this  apparatus  to  war- 
rant a  statement  as  to  its  accuracy;  the  indications  are, 
however,  that  it  will  give,  with  some  modifications,  a  simple 
method  of  making  a  quantitative  determination  of  the  bac- 
teria in  a  unit  volume  of  air. 


METHODS  AND  DEVICES  EMPLOYED  77 

(2)     SAND  FILTER:     (See  Plates  14  and  15,  page  94.) 

The  apparatus  for  making  quantitative  bacterial  deter- 
minations consists  of  the  following: 

A  small  gas  meter  is  used  for  measuring  the  air.  On 
the  inlet  of  the  meter  a  glass  filter  is  fastened,  as  shown  in 
the  accompanying  illustration.  This  filter  contains  sand  to 
a  depth  of  1.5  centimeters,  the  sand  being  sifted  through  100 
mesh  wire  screen.  Air  is  drawn  through  the  meter  by  a 
high  pressure  centrifugal  blower.  From  10  to  50  cubic  feet 
of  air  are  usually  drawn  through  the  apparatus.  The  sand 
is  shaken  in  sterile  water  and  allowed  to  settle.  A  measured 
portion  of  the  water  is  plated  in  agar,  incubated  and  the 
number  of  colonies  counted. 

C — CABINET  TEST  METHODS. 

(1)  BLOOD  PRESSURE  (SPHYGMOMANOMETER)  :  See  Plates 
16  and  17,  page  95.) 

For  determining  blood  pressures  in  cabinet  test  experi- 
ments, a  diaphragm  dial  Sphygmomanometer  is  used.  The 
manometer  proper  consists  of  two  free  connecting  air  cham- 
bers, the  diaphragm  of  one  being  so  connected  to  the  needle 
on  the  dial  that  changes  of  pressure  are  indicated  directly 
in  millimeters. 

The  pressure  determining  apparatus  consists  of  a  cloth 
covered  rubber  bag  9  inches  long  and  5  inches  wide,  pro- 
vided with  two  short  rubber  tubes  connecting  with  the  inte- 
rior. The  bag  is  wrapped  around  the  arm  of  the  subject, 
the  manometer  attached  to  one  of  the  tubes  and  the  inflating 
bulb  to  the  other.  The  bulb  is  also  provided  with  a  release 
valve  so  that  the  pressure  in  the  sleeve  may  be  reduced  and 
accurately  controlled. 

In  order  to  obtain  a  clear  understanding  of  the  use  of 
this  apparatus,  it  is  necessary  first  to  understand  the  prin- 
ciple on  which  it  operates. 

Each  heart  beat  is  composed  of  two  parts,  the  systole 
or  contraction,  at  which  time  the  blood  is  forced  out  and 
into  the  arterial  system,  and  the  diastole,  or  expansion, 
when  the  heart  relaxes  and  blood  from  the  venous  system 
re-enters  the  heart. 


78  METHODS  AND  DEVICES  EMPLOYED 

The  resistance  in  the  circulatory  system  is  made  up  of 
friction  of  the  blood  passing  through  the  vessels  and  the 
work  performed  in  expanding  them.  This  may  be  con- 
sidered as  the  static  pressure  against  which  the  heart  oper- 
ates. 

The  pressure  recorded  during  the  contraction  of  the 
heart  is  the  highest  and  is,  therefore,  the  maximum  pres- 
sure. 
METHOD  OF  USING:    (See  Plate  17,  page  95.) 

If  now  the  rubber  bag  or  sleeve  is  carefully  adjusted  on 
the  arm  of  the  subject  and  air  pumped  into  the  same  until 
the  pressure  of  the  bag  obliterates  the  pulse  at  the  wrist, 
the  pressure  will  be  greater  than  the  maximum  pressure  of 
the  arterial  system.  With  the  release  valve  the  pressure  is 
now  carefully  reduced  until  the  pulse  is  again  just  percept- 
ible. At  this  point  the  dial  indicates  the  maximum  pressure 
of  the  arterial  system  in  millimeters  of  mercury. 

The  pressure  is  now  further  reduced  until  every  pulse 
beat  is  distinctly  shown  by  the  movement  of  the  needle.  At 
the  point  where  the  needle's  excursion  at  each  beat  is  the 
greatest  will  be  the  point  of  minimum  pressure,  corre- 
sponding to  the  resistance  offered  to  the  flow  of  blood  by 
the  circulatory  system.  The  difference  between  the  maxi- 
mum and  minimum  pressure  will  be  the  pulse  pressure  or 
the  surplus  which  the  heart  exerts  above  the  resistance 
encountered.  The  maximum  pressure  in  a  normal  adult 
male  ranges  from  105  to  145  millimeters.  The  normal  min- 
imum pressure  ranges  from  25  to  40  millimeters  below  the 
maximum.  The  normal  pulse  pressure  ranges  from  25  to  40 
millimeters. 

( 2 )  TEMPEKATUEES  : 

These  are  taken  with  standard  Fahrenheit  thermom- 
eters graduated  from  — 10  to  +120  degrees  at  two  loca- 
tions at  the  floor  line  and  two  locations  at  the  ceiling.  One 
recording  thermometer  3  feet  above  the  floor  line  is  used  as 
a  check  on  the  other  observations. 

(3)  PSYCHKOMETER :    (See  Plate  18,  page  96.) 

The  psychrometers  used  are  of  the  standard  sling  pat- 
tern adopted  by  the  United  States  Weather  Bureau  of  the 
Department  of  Agriculture,  illustrated  herewith.  In  taking 


METHODS  AND  DEVICES  EMPLOYED  79 

readings,  the  wet  bulb  is  thoroughly  saturated  and  the 
instrument  swung  for  fifteen  or  twenty  seconds  and  a  read- 
ing taken.  The  instrument  is  now  swung  again,  the  pre- 
vious reading  of  the  wet  bulb  being  kept  in  mind.  This 
operation  is  repeated  until  the  wet  bulb  reaches  the  lowest 
point  on  the  scale  and  begins  to  ascend,  when  the  observa- 
tions of  the  wet  and  dry  bulb  temperatures  are  recorded. 

The  relative  humidity  determinations  are  taken  from  a 
humidity  chart  prepared  by  the  Carrier  Air  Conditioning 
Company  of  America. 

(4)  AIR  SAMPLES: 

Air  samples  are  taken  and  analyzed  for  carbon  dioxide 
according  to  the  method  described  under  appendix  "A." 

(5)  BACTERIA: 

Cultures  are  taken  as  described  under  appendix  "B." 

D — DUST. 

(1)     SUGAR  FILTER: 

The  filter  for  determining  the  amount  of  dust  in  a  unit 
volume  of  air  is  described  under  appendix  "B"  for  quan- 
titative determinations  of  bacteria,  except  that  sugar  is  sub- 
stituted for  sand  in  the  filter.  The  filters  are  prepared  as 
follows : 

Twenty-five  grams  of  sugar  are  used  in  the  filter.  This 
is  sifted  through  a  25-mesh  wire  screen  and  again  on  a  100- 
mesh  wire  screen.  The  sugar  used  is  that  which  is  retained 
on  the  100-mesh  wire  screen.  Before  beginning  a  test  a 
large  quantity  of  sugar  is  sifted  and  a  control  count  made. 
After  collecting  the  sample,  the  sugar  is  dissolved  in  100  cc 
of  distilled  water,  the  water  agitated  and  the  sample  placed 
in  a  Sedgwick-Kafter  counting  cell  and  the  count  made. 
(See  Plate  19,  page  97.) 

The  Sedgwick-Rafter  counting  cell  is  made  by  cement- 
ing a  rectangular  brass  rim  on  an  ordinary  glass  slide.  The 
internal  dimensions  of  the  cell  are :  Length,  50  millimeters ; 
width,  20  millimeters ;  and  depth,  1  millimeter,  giving  it  an 
area  of  1,000  square  millimeters,  and  a  capacity  of  1  cubic 
centimeter.  A  thick  cover  glass  (No.  3)  having  dimensions 
the  same  as  those  of  the  outside  of  the  brass  rim  forms  the 


80  METHODS  AND  DEVICES  EMPLOYED 

roof  of  the  cell.  The  cell  and  cover  glass  are  thoroughly 
cleaned  and  the  latter  placed  diagonally  over  the  top  of  the 
cell,  so  that  an  opening  is  left  at  either  end.  One  cc  of  the 
solution  is  now  introduced  by  means  of  a  small  pipette  at 
one  side  of  the  cover  glass,  the  air  escaping  through  the 
other.  The  glass  is  now  turned  to  cover  the  cell,  which  is 
now  ready  for  the  count. 

An  ocular  micrometer,  consisting  of  a  square,  ruled 
upon  a  thin  disc  of  glass,  is  placed  upon  the  diaphragm  of 
the  ocular  of  the  miscroscope.  The  square  is  of  such  size 
that  with  a  certain  combination  of  objectives  (No.  3  Leitz) 
and  ocular  (No.  4  Leitz)  and  with  a  certain  tube  length  of 
the  miscroscope,  the  area  covered  by  it  on  the  stage  is  just 
1  square  millimeter.  The  large  square  is  1  square  milli- 
meter and  with  the  ocular  we  have  been  using  the  small 
squares  are  1/36  of  a  square  millimeter. 

The  tube  length  was  determined  by  comparison  with 
the  Thoma-  Zeise  blood  counting  cell.  The  cell  filled  with 
the  solution  is  placed  upon  the  microscope  stage  and  the 
dust  particles  within  a  ruled  square  are  counted  in  a  num- 
ber of  representative  fields.  Inasmuch  as  some  of  the  par- 
ticles are  light  and  rise  to  the  top,  while  others  are  heavy 
and  sink  to  the  bottom,  the  focus  of  the  microscope  must  be 
constantly  changed  to  include  all  of  these  particles. 

The  number  of  dust  particles  in  one  cubic  foot  is  then 
determined  in  the  following  manner : 

Let  A — represent  total  number  of  particles  counted. 
B — represent  number  of  squares  counted. 
C — represent  dilution  of  the  sample. 
D — represent  number  of  cubic  feet  in  sample. 

A        1 000 

^-x— ^ — =  number  of  dust  particles  in  1  cubic  foot  of  air. 

SOURCES  OF  ERROR: 

1 — Particles  adhering  to  the  filter. 

2 — Particles  of  dust  in  any  of  the  apparatus  used  in  the 
dilution  water. 

3 — Disintegration  of  dust  particles  in  the  solution. 

4 — Presence  of  unnoticed  dust  in  the  objective  or  ocular 
or  on  the  micrometer  or  the  mirror  of  the  micro- 
scope, or  on  the  cover  glass  of  the  cell.  The  mirror 


METHODS  AND  DEVICES  EMPLOYED  81 

on  the  microscope  and  the  glass  cover  are  especially 
liable  to  gather  dust,  even  during  the  progress  of 
counting.  To  avoid  errors  control  counts  must  be 
made  on  all  samples  of  sugar  and  duplicate  samples 
should  be  taken  and  counted,  all  apparatus  care- 
fully washed  with  soap  and  water  and  rinsed  with 
distilled  water.  The  count  should  be  made  as  soon 
as  possible  after  dissolving  the  sugar.  The  micro- 
scope must  be  carefully  cleaned  and  the  slide,  mir- 
ror, and  objectives  examined  from  time  to  time 
during  the  progress  of  the  count  to  see  that  they  are 
free  from  dust. 
(1)  KONISCOPE:  (See  Plate  20,  page  97.) 

This  is  the  original  instrument  devised  by  Professor 
John  Aitken  for  determining  the  amount  of  dust  in  air.  The 
principle  on  which  it  operates  depends  upon  the  well  known 
physical  fact  that  in  saturated  air,  water  condenses  in 
minute  droplets  on  every  dust  particle,  if  the  dew  point  is 
lowered  either  by  reducing  the  temperature  or  the  pressure. 
The  apparatus  consists  of  an  observation  tube  about  22 
inches  long  provided  with  an  eye  piece  at  the  proximal  end, 
and  an  observation  window  at  the  distal  end.  The  tube  is 
lined  with  hygroscopic  material  throughout  its  entire 
length.  Connected  to  the  observation  tube  near  the  eye 
piece  is  a  hand  exhaust  pump.  At  the  other  end  of  the  tube 
a  stop  cock  is  provided  for  introducing  the  air  to  be  sam- 
pled. In  using  the  apparatus  the  hygroscopic  lining  is  sat- 
urated with  water.  The  stop  cock  is  now  open  and  by  oper- 
ating the  pump,  the  air  sample  is  drawn  into  the  tube.  The 
stop  cock  is  now  closed  and  by  one  or  two  quick  movements 
of  the  piston  the  air  in  the  tube  is  rarified,  the  dew  point 
is  consequently  lowered,  and  a  minute  drop  of  moisture  con- 
denses on  each  dust  particle,  forming  a  dust  fog  or  haze 
which  is  observed  through  the  eye  piece.  The  density  and 
color  of  this  fog  is  compared  with  a  chart  provided,  which 
gives  the  relative  amount  of  dust  in  the  sample. 

Owing  to  the  personal  element  involved  in  the  use  of 
this  apparatus  its  value  is  questionable,  except  where 
always  used  by  the  same  person,  and  even  then  the  results 
are  only  relative. 


82  METHODS  AND  DEVICES  EMPLOYED 

(3)     AITKEN  POKTABLE  DUST  COUNTER  :    (See  Plate  21,  page 
98.) 

Owing  to  the  limited  application  of  the  Koniscope,  for 
the  reasons  just  enumerated,  Professor  Aitken  has  devel- 
oped the  principle  of  moisture  condensing  on  the  dust  par- 
ticles, when  the  dew  point  is  lowered,  in  the  design  of  his 
new  machine.  Instead  of  observing  the  density  or  color  of 
the  haze  produced,  the  dust  particles,  with  their  attendant 
droplets  of  moisture,  are  precipitated  on  a  ruled  object 
glass  and  counted.  If  now  a  definite  quantity  of  the  air  to 
be  examined  is  saturated,  and  precipitation  made  the  num- 
ber of  dust  particles,  with  slight  magnification,  can  be  read- 
ily observed  and  counted. 

This  machine  consists  of  a  precipitation  chamber  with 
pump,  filter,  eye  piece,  etc.,  mounted  on  a  tripod  in  a  very 
convenient  and  portable  manner.  The  precipitation  cham- 
ber (a)  holds  exactly  50  cubic  centimeters.  The  stop  cocks 
(b  and  c)  are  bored  and  calibrated  to  hold  %  and  1/20  of  a 
cubic  centimeter  each.  The  chambers  of  these  cocks  are 
bored  horizontally  as  well  as  vertically,  so  that  air  may  be 
passed  through  from  the  filter,  or  a  measured  quantity 
introduced  from  the  outside.  These  are  situated  between 
the  filter  (d)  and  the  precipitation  chamber.  If  these  cocks 
are  set  longitudinally  and  the  pump  (e)  operated,  the  air 
is  drawn  into  the  opening  (o)  through  the  filter  and  into 
the  precipitation  chamber.  The  pump  piston  is  depressed 
10  or  12  times  in  this  manner,  removing  all  of  the  residual 
air  and  dust  in  the  apparatus. 
METHOD  OF  OPERATION: 

The  stop  cocks  (c  and  x)  are  closed  and  the  pump  pis- 
ton depressed  once.  This  slightly  rarifies  the  air  in  the  pre- 
cipitation chamber.  The  three-way  cock  (b)  is  now  turned 
horizontally  and  the  bore  filled  with  the  air  to  be  sampled, 
by  means  of  the  rubber  tube  (n).  It  is  then  turned  verti- 
cally, the  stop  cock  (x)  opened  and  the  negative  pressure, 
caused  by  the  previous  depression  of  the  pump  piston, 
draws  the  air  into  the  precipitation  chamber.  By  means 
of  the  stirring  rod  (g)  the  sample  is  now  mixed  until  the 
air  is  saturated.  The  stop  cock  (x)  is  closed  and  the  pump 
piston  again  depressed.  Looking  through  the  eye  piece  (n) 


METHODS  AND  DEVICES  EMPLOYED  J  S3 

a  fine  shower  of  rain  is  observed  to  fall  on  the  ruled  object 
glass,  where  the  droplets  are  counted. 

Noting  the  dilution  of  the  sample  and  counting  the  num- 
ber of  dust  particles  in  a  given  portion  the  total  number  of 
dust  particles  per  cubic  centimeter  of  air  is  calculated,  the 
formula  being  as  follows : 

A — represents  total  number  of  particles  counted. . 

B — represents  total  number  of  squares  counted. 

C — represents  dilution  of  samples. 

^-  x  100  C  =  the  number  of  dust  particles  per  cubic  centi- 
meter. 

If  the  upper  stop  cock  is  used  C  will  be  200 ;  if  the  lower 
is  used  C  will  be  1,000.  As  each  square  is  one  square  milli- 
meter in  area  and  one  centimeter  high  its  cubic  content  is 
.01  of  a  cubic  centimeter.  C  must,  therefore,  be  multiplied 
by  100  to  obtain  the  average  number  of  particles  per  cubic 
centimeter. 

A  modification  of  the  method,  suggested  by  Mr.  Hoskins 
is  to  insert  a  smoked  cover  glass  on  the  ruled  objective. 
The  precipitation  then  makes  a  permanent  record,  which  is 
removed  and  preserved.    (See  Plate  22,  page  99.) 
STANDAKD  CANDLES  : 

Candles  employed  in  theater  tests  are  of  pure  paraffin 
wax  1%  inches  in  diameter  and  6  inches  high.  By  careful 
test  they  decrease  in  weight  9.8  grams  per  hour.  The  heat 
units  given  off  as  determined  by  the  bomb  calorimeter  gives 
370  B.  T.  U.  per  hour.  The  amount  of  carbon  dioxide  pro- 
duced is  .48  of  a  cubic  foot  per  hour.  Each  candle,  there- 
fore, very  closely  approximates  the  heat  and  carbon  dioxide 
production  of  two  adult  persons,  per  unit  of  time. 


METHODS  AND  DEVICES  EMPLOYED  >,t  ., 


Plate  No.  1.     Desk  in  Experimental  School  Room  showing 
individual  air  supply.     See  page  43. 


;  .METHODS   A^I)   DEVICES   EMPLOYED 


Plate  No.  2.     Experimental  School  Room.     See  page  43. 


Plate  No.  3.     Test  Cabinet.     See  pages  60  and  61, 


METHODS  AND   DEVICES   E/MFJ^Q^ED   '  \ '',  \  .     87 


Plate  No  4.     Anemometer.     See  page  71, 


Plate  No.  5.     Pilot  Tubes.     See  page  72. 


88  '  ''  :  •'' 'METHODS' 'AND'  DEVICES   EMPLOYED 


Plate  No.  6.     Ellison  Draft  Gauge.     See  page  72. 


Plate  No.  7.     Ammonium  Chloride  Apparatus.     See  page  73. 


METHODS  AND   DEVICES 


Plate  No.  8.     Phenolphthalein  Test  Tubes. 
See  page  73. 


Plate  No.  9.     Air  Sampling  Device.     Paquelin  Cautery.     See  page  74, 


90    .  |  ,ic  ^:  ;  V!ta&T&&ps 


DEVICES  EMPLOYED 


Plate  No.  10.     Analyses  of  Air  Samples.     Petterson-Palmquist 
Apparatus.      See  page  75. 


METHODS  AND    DEVICES 


91 


Plate  No.  11.     Petterson-Palmquist 
Apparatus.     See  page  75. 


92  ,     ,,     ,    .METHODS  AND   DEVICES   EMPLOYED 


Plate  No.  12.     Petterson-Palmquist 
Apparatus.     See  page  75. 


METHODS  AND  DEVICES  EMPLOYED 


,  ,    .     93 


Plate  No.  13.     Culture  Plate.     See  page  76. 


94    .<,...       ,    ME,THOI)S  ^AJSTD   DEVICES   EMPLOYED 


Plate  No.  14.     Sand  Filter.     See  page  77. 


\\l 


-JFilter 


Meter 


F.'lter 


Plate  No.  15.     Sand  Filter.     See  page  77. 


METHODS  AND  DEVICES  EMPLOYED-    : .;  :\:  :  ;;J95 


Plate  No.  16.     Method  of  using  Sphygmomanometer.     See  page  77. 


Plate  No.  17.     Sphygmomanometer.     See  page  78. 


AND  DEVICES  EMPLOYED 


Plate  No.  18.     Psychrometer. 
See  page  78. 


METHODS  AND  DEVICES  EMPLOYED 


Plate  No.  20.     Koniscope. 
See  page  81. 


Plate  No.  19.     Sedgwick- 

Rafter  Counting  Cell 

on   Microscope. 

See  page  79. 


&ET!l£>DS:  AND   DEVICES   EMPLOYED 


Plate  No.  21.     Aitken  Portable  Dust 
Counter.     See  page  82. 


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